Security versus Computation Time in IV-ACOPF with SOCP Initialization

Abstract. The Sympson-Hetter (1985) method provides a means of controlling maximum exposure rate of items in Computerized Adaptive Testing. Through a series of simulations, control parameters are set that mark the probability of administration of an item on being selected. This method presents two main problems: it requires a long computation time for calculating the parameters and the maximum exposure rate is slightly above the fixed limit. Van der Linden (2003) presented two alternatives which appear to solve both of the problems. The impact of these methods in the measurement accuracy has not been tested yet. We show how these methods over-restrict the exposure of some highly discriminating items and, thus, the accuracy is decreased. It also shown that, when the desired maximum exposure rate is near the minimum possible value, these methods offer an empirical maximum exposure rate clearly above the goal. A new method, based on the initial estimation of the probability of administration and the probability of selection of the items with the restricted method ( Revuelta & Ponsoda, 1998 ), is presented in this paper. It can be used with the Sympson-Hetter method and with the two van der Linden's methods. This option, when used with Sympson-Hetter, speeds the convergence of the control parameters without decreasing the accuracy.

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Double Precision Is Not Needed for Many-Body Calculations: New Conventional Wisdom

10.26434/chemrxiv.6104804.v1 ◽

2018 ◽

Author(s):

Pavel Pokhilko ◽

Evgeny Epifanovsky ◽

Anna I. Krylov

Keyword(s):

Large Scale ◽

Computation Time ◽

Coupled Cluster ◽

Double Precision ◽

Many Body ◽

Single Precision ◽

Parallel Performance ◽

Point Representation ◽

Electron Repulsion Integrals ◽

Cluster Methods

Using single precision floating point representation reduces the size of data and computation time by a factor of two relative to double precision conventionally used in electronic structure programs. For large-scale calculations, such as those encountered in many-body theories, reduced memory footprint alleviates memory and input/output bottlenecks. Reduced size of data can lead to additional gains due to improved parallel performance on CPUs and various accelerators. However, using single precision can potentially reduce the accuracy of computed observables. Here we report an implementation of coupled-cluster and equation-of-motion coupled-cluster methods with single and double excitations in single precision. We consider both standard implementation and one using Cholesky decomposition or resolution-of-the-identity of electron-repulsion integrals. Numerical tests illustrate that when single precision is used in correlated calculations, the loss of accuracy is insignificant and pure single-precision implementation can be used for computing energies, analytic gradients, excited states, and molecular properties. In addition to pure single-precision calculations, our implementation allows one to follow a single-precision calculation by clean-up iterations, fully recovering double-precision results while retaining significant savings.

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Segmentasi Citra Mri Menggunakan Deteksi Tepi Untuk Identifikasi Kanker Payudara

Matrik Jurnal Manajemen Teknik Informatika dan Rekayasa Komputer ◽

10.30812/matrik.v15i2.38 ◽

2017 ◽

Vol 15 (2) ◽

pp. 17 ◽

Cited By ~ 1

Author(s):

Ervina Varijki ◽

Bambang Krismono Triwijoyo

Keyword(s):

Breast Cancer ◽

Edge Detection ◽

Object Segmentation ◽

Computation Time ◽

Input Image ◽

Boundary Line ◽

Cancer Breast ◽

Average Computation Time ◽

Breast Cancer Mri ◽

Image Format

One type of cancer that is capable identified using MRI technology is breast cancer. Breast cancer is still the leading cause of death world. therefore early detection of this disease is needed. In identifying breast cancer, a doctor or radiologist analyzing the results of magnetic resonance image that is stored in the format of the Digital Imaging Communication In Medicine (DICOM). It takes skill and experience sufficient for diagnosis is appropriate, andaccurate, so it is necessary to create a digital image processing applications by utilizing the process of object segmentation and edge detection to assist the physician or radiologist in identifying breast cancer. MRI image segmentation using edge detection to identification of breast cancer using a method stages gryascale change the image format, then the binary image thresholding and edge detection process using the latest Robert operator. Of the20 tested the input image to produce images with the appearance of the boundary line of each region or object that is visible and there are no edges are cut off, with the average computation time less than one minute.

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Efficient Computing in Image Processing and DSPs with ASIP Based Multiplier

Recent Patents on Engineering ◽

10.2174/1872212112666180810150357 ◽

2019 ◽

Vol 13 (2) ◽

pp. 174-180

Author(s):

Poonam Sharma ◽

Ashwani Kumar Dubey ◽

Ayush Goyal

Keyword(s):

Image Processing ◽

High Speed ◽

Computation Time ◽

Digital Signal ◽

Instruction Set ◽

Computationally Efficient ◽

Specific Instruction ◽

Processor Core ◽

Speed Performance ◽

Application Specific

Background: With the growing demand of image processing and the use of Digital Signal Processors (DSP), the efficiency of the Multipliers and Accumulators has become a bottleneck to get through. We revised a few patents on an Application Specific Instruction Set Processor (ASIP), where the design considerations are proposed for application-specific computing in an efficient way to enhance the throughput. Objective: The study aims to develop and analyze a computationally efficient method to optimize the speed performance of MAC. Methods: The work presented here proposes the design of an Application Specific Instruction Set Processor, exploiting a Multiplier Accumulator integrated as the dedicated hardware. This MAC is optimized for high-speed performance and is the application-specific part of the processor; here it can be the DSP block of an image processor while a 16-bit Reduced Instruction Set Computer (RISC) processor core gives the flexibility to the design for any computing. The design was emulated on a Xilinx Field Programmable Gate Array (FPGA) and tested for various real-time computing. Results: The synthesis of the hardware logic on FPGA tools gave the operating frequencies of the legacy methods and the proposed method, the simulation of the logic verified the functionality. Conclusion: With the proposed method, a significant improvement of 16% increase in throughput has been observed for 256 steps iterations of multiplier and accumulators on an 8-bit sample data. Such an improvement can help in reducing the computation time in many digital signal processing applications where multiplication and addition are done iteratively.

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Numerical Simulation of Solidification Process for a Machine Tool Bed

Materials Science Forum ◽

10.4028/www.scientific.net/msf.675-677.987 ◽

2011 ◽

Vol 675-677 ◽

pp. 987-990

Author(s):

Ling Tang ◽

Xu Dong Wang ◽

Hai Jing Zhao ◽

Man Yao

Keyword(s):

Heat Transfer ◽

Temperature Field ◽

Temperature Distribution ◽

Machine Tool ◽

Computation Time ◽

Solidification Process ◽

Field Calculation ◽

Original Design ◽

Calculation Results ◽

Improved Design

In this paper, the flow, heat transfer and stress during solidification process of the machine tool bed weighed about 2.5ton that has been optimized by structural topologymethod, was calculated with ProCAST software, and the causes of the crack forming in the casting of the machine tool bed was analysed. According to the calculation results, the structural design of the local part where cracks tends to form has been improved, and the heat transfer and the stress are calculated again. By comparing the temperature field with filling of molten cast iron and without filling, it has been found that there was little effect of filling on the results of temperature distribution of the cast, therefore the effect of filling can be ignored in the following temperature field calculation to save computation time. The model has been simplified in the stress field calculation with considering the complexity of the machine tool bed and the cost of computation. Then, the merits and demerits of the original design and the improved design are compared and analyzed depending on the calculated temperature and stress results. It is suggested that the improved one could get a more uniform temperature distribution and then the trend of the crack occurring can be greatly reduced. These results could provide a guide for the actual casting production, achieving the scientific control of the production of castings, ensuring the quality of the castings.

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Sound Localization for Ad-Hoc Microphone Arrays

Energies ◽

10.3390/en14123446 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3446

Author(s):

Muhammad Usman Liaquat ◽

Hafiz Suliman Munawar ◽

Amna Rahman ◽

Zakria Qadir ◽

Abbas Z. Kouzani ◽

...

Keyword(s):

Sound Localization ◽

Sound Source ◽

Ad Hoc ◽

Dimensional Space ◽

Computation Time ◽

Location Estimation ◽

Microphone Arrays ◽

Sound Signal ◽

Experimental Arrangement ◽

Advantages And Disadvantages

Sound localization is a field of signal processing that deals with identifying the origin of a detected sound signal. This involves determining the direction and distance of the source of the sound. Some useful applications of this phenomenon exists in speech enhancement, communication, radars and in the medical field as well. The experimental arrangement requires the use of microphone arrays which record the sound signal. Some methods involve using ad-hoc arrays of microphones because of their demonstrated advantages over other arrays. In this research project, the existing sound localization methods have been explored to analyze the advantages and disadvantages of each method. A novel sound localization routine has been formulated which uses both the direction of arrival (DOA) of the sound signal along with the location estimation in three-dimensional space to precisely locate a sound source. The experimental arrangement consists of four microphones and a single sound source. Previously, sound source has been localized using six or more microphones. The precision of sound localization has been demonstrated to increase with the use of more microphones. In this research, however, we minimized the use of microphones to reduce the complexity of the algorithm and the computation time as well. The method results in novelty in the field of sound source localization by using less resources and providing results that are at par with the more complex methods requiring more microphones and additional tools to locate the sound source. The average accuracy of the system is found to be 96.77% with an error factor of 3.8%.

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Strong-axis response of steel I-sections subjected to close-in detonations

International Journal of Protective Structures ◽

10.1177/2041419620984487 ◽

2020 ◽

pp. 204141962098448

Author(s):

Hezi Y Grisaro ◽

Michael V Seica ◽

Jeffrey A Packer ◽

Wei Li

Keyword(s):

Computation Time ◽

Structural Member ◽

Local Damage ◽

Structural Members ◽

Large Magnitude ◽

Single Degree Of Freedom ◽

Charge Shape ◽

Dynamic Scenario ◽

Detonation Process ◽

Residual Deformations

The analysis of structural members subjected to close-in detonations involves a complicated dynamic scenario. Since the charge is very close to the structural member, the reflected pressure distribution on the member surface is highly non-uniform. In addition, the level of damage to the structural member may be high because of the large magnitude of the load. Due to these phenomena, the response of a structural member to close-in detonation cannot be accurately modelled by relatively simple methods like single-degree of freedom models, and more complicated models are required. Such models need to include numerical simulation of the detonation process, which produces a non-uniform pressure environment, allowing the pressure to reflect and flow around the member section. The local damage and flow around the section are especially of interest in I-shaped, or wide-flange-section members. Herein, the response of such sections is modelled by numerical simulations using a novel technique, which overcomes the difficulty of computation time, and is validated through various calculations. The model is used to perform a parametric study to investigate the response of I-sections subjected to close-in detonations, in terms of local damage and global behaviour, with scaled distances of 0.15–0.29 m/kg1/3 and loading causing flexure about the strong axis. Various aspects that affect the performance are studied, such as: the effect of scaled distance, the addition of welded stiffening plates between the flanges and web, the effect of boundary conditions and the effect of charge shape. Resulting local damage and residual deformations are assessed for the cases studied.

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Approximation of continuous random variables for the evaluation of the reliability parameter of complex stress–strength models

Annals of Operations Research ◽

10.1007/s10479-021-04010-6 ◽

2021 ◽

Author(s):

Alessandro Barbiero ◽

Asmerilda Hitaj

Keyword(s):

Order Approximation ◽

Linear Optimization ◽

Closed Form Solution ◽

Random Variables ◽

Discrete Distribution ◽

Computation Time ◽

Form Solution ◽

Engineering Problem ◽

Approximation Technique ◽

Reliability Parameter

AbstractIn many management science or economic applications, it is common to represent the key uncertain inputs as continuous random variables. However, when analytic techniques fail to provide a closed-form solution to a problem or when one needs to reduce the computational load, it is often necessary to resort to some problem-specific approximation technique or approximate each given continuous probability distribution by a discrete distribution. Many discretization methods have been proposed so far; in this work, we revise the most popular techniques, highlighting their strengths and weaknesses, and empirically investigate their performance through a comparative study applied to a well-known engineering problem, formulated as a stress–strength model, with the aim of weighting up their feasibility and accuracy in recovering the value of the reliability parameter, also with reference to the number of discrete points. The results overall reward a recently introduced method as the best performer, which derives the discrete approximation as the numerical solution of a constrained non-linear optimization, preserving the first two moments of the original distribution. This method provides more accurate results than an ad-hoc first-order approximation technique. However, it is the most computationally demanding as well and the computation time can get even larger than that required by Monte Carlo approximation if the number of discrete points exceeds a certain threshold.

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Practical Cross-Layer Radio Frequency-Based Authentication Scheme for Internet of Things

Sensors ◽

10.3390/s21124034 ◽

2021 ◽

Vol 21 (12) ◽

pp. 4034

Author(s):

Arie Haenel ◽

Yoram Haddad ◽

Maryline Laurent ◽

Zonghua Zhang

Keyword(s):

Internet Of Things ◽

Radio Frequency ◽

Real Life ◽

Computation Time ◽

Cost Effective ◽

Battery Life ◽

Cross Layer ◽

Security Level ◽

Cost Of Energy ◽

Iot Devices

The Internet of Things world is in need of practical solutions for its security. Existing security mechanisms for IoT are mostly not implemented due to complexity, budget, and energy-saving issues. This is especially true for IoT devices that are battery powered, and they should be cost effective to be deployed extensively in the field. In this work, we propose a new cross-layer approach combining existing authentication protocols and existing Physical Layer Radio Frequency Fingerprinting technologies to provide hybrid authentication mechanisms that are practically proved efficient in the field. Even though several Radio Frequency Fingerprinting methods have been proposed so far, as a support for multi-factor authentication or even on their own, practical solutions are still a challenge. The accuracy results achieved with even the best systems using expensive equipment are still not sufficient on real-life systems. Our approach proposes a hybrid protocol that can save energy and computation time on the IoT devices side, proportionally to the accuracy of the Radio Frequency Fingerprinting used, which has a measurable benefit while keeping an acceptable security level. We implemented a full system operating in real time and achieved an accuracy of 99.8% for the additional cost of energy, leading to a decrease of only ~20% in battery life.

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An efficient procedure to predict the dynamic loads for piston liner systems in marine engines

International Journal of Engine Research ◽

10.1177/1468087421996988 ◽

2021 ◽

pp. 146808742199698

Author(s):

Lyu Xiuyi ◽

Abdullah Azam ◽

Wang Yuechang ◽

Lu Xiqun ◽

Li Tongyang ◽

...

Keyword(s):

Simulation Analysis ◽

Structural Parameters ◽

Computation Time ◽

Primary Source ◽

Cylinder Liner ◽

Accurate Method ◽

Friction Behavior ◽

Accuracy Requirement ◽

Precise Prediction ◽

Friction Prediction

The piston ring-cylinder liner (PRCL) is one of the most important parts of marine diesel engines and contributes 25% to 50% of total friction loss. The lubrication simulation analysis of the PRCL system is a challenging task. Complete understanding and precise prediction of lubrication loads is a key to understanding the friction behavior of PRCL systems as the accuracy of the friction prediction depends upon precise prediction of lubrication loads. Therefore, this paper focuses on the gas pressure calculation which is the primary source of lubrication loads. The procedure presented combines the advantages of two mainstream methods to predict loads in the PRCL system. The result is a significant reduction in the computation time without compromising on accuracy. Firstly, a comparison of both approaches is presented which suggests that each technique has its limitations (one is time-bound, and one is accuracy-bound). Then, the results from both calculation methods are verified against literature and a parametric study is performed to identify the key structural parameters of PRCL system that affect the calculation efficiency. Finally, a correlation coefficient is introduced into the analysis to combine the two approaches which then identifies the conditions under which the use of the faster method becomes invalid and replaces it with the more accurate approach. This ensures optimum performance of the calculation procedure by switching between the fast and the accurate method depending upon the accuracy requirement under given conditions, thereby, simplifying the dynamic and lubrication model of PRCL systems. The study has direct implications for the tribological design of the PRCL interface.

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