A Reconfiguration Algorithm for the Single-Driven Hexapod-Type Parallel Mechanism

This paper presents a hexapod-type reconfigurable parallel mechanism that operates from a single actuator. The mechanism design allows reproducing diverse output link trajectories without using additional actuators. The paper provides the kinematic analysis where the analytical relationships between the output link coordinates and actuated movement are determined. These relations are used next to develop an original and computationally effective algorithm for the reconfiguration procedure. The algorithm enables selecting mechanism parameters to realize a specific output link trajectory. Several examples demonstrate the implementation of the proposed techniques. CAD simulations on a mechanism virtual prototype verify the correctness of the suggested algorithm.

A Secure Environment Using a New Lightweight AES Encryption Algorithm for E-Commerce Websites

Providing security for transmitted data through the e-commerce environment requires using a fast and high secure encryption algorithm. Balancing between the speed and the security degree is a problem that many of the encryption algorithms suffer from. Increasing the security degree requires increasing the level of complexity which results in increasing encryption time. On the other hand, increasing the algorithm speed may reduce the complexity degree which affects the security level. This paper aims to design an encryption algorithm that balances time and complexity (speed and security). This is done by suggesting a security environment that depends on creating and providing an agent software to be settled into each customer device that manages the purchase and security process without customer interference. The suggested encryption algorithm is applied within this environment. Several modifications are performed on the AES encryption algorithm. The AES was chosen due to its performance (security and speed), which makes it suitable for encrypting transmitted data over the Internet. These modifications involve adding preprocessing steps (padding and zigzag), eliminating Sub Byte step, and reducing the number of rounds. The experimental results showed that the suggested algorithm provides more security and speed in the encryption and decryption process. The randomness degree has increased by 29.5%. The efficiency is increased because the encryption and decryption times are reduced, as is the CPU usage. The throughput for the suggested algorithm is increased by 10% for the encryption process and is increased by 9.3% for the decryption process.

Mathematical modeling of signals, linear links and responses of telecommunications and radioelectronics systems in time domain

A single mathematical model of time characteristics of signals, links and responses of telecommunications and radioelectronics systems is suggested. It embodies Dirac- and Heaviside responses of all types of linear links, as well as their responses to the input in the form of periodic signals, no periodic finite and no periodic eternal signals. On the basis of the suggested model the algorithm for calculation of time characteristics was developed, which allows creation of effective automated simulations procedure of signals, links and responses in time-domain. The comparative quantitative analysis of accuracy of the suggested algorithm and discrete Fourier transformation (DFT) algorithm was carried out.

A New Approach Based on Matching Theory and Simulated Annealing for Parallel Machine Scheduling Problems

As an extension of the classical Parallel Machine Scheduling Problem (PMSP), Unrelated Parallel Machine Scheduling Problem (UPMSP) is a much substantial issue in the modern manufacturing environment. It has been demonstrated to be a NP-hard problem. This research suggests a hybrid algorithm that combines Matching Theory (MT) and Simulated Annealing (SA) for solving an UPMSP with sequence-dependent setup time aimed at minimizing the total completion time. The hybrid algorithm is based on allocation of works to the best machine that can do it, and the determination of the order in which jobs have to be handled on the machines. The hybridization of MT and SA that integrates the features of these two individual parts is the main innovation aspect of the strategy. MT encourages the convergence, while SA promotes the diversity. Therefore, the designed algorithm can balance the intensification and diversification very well. Some tests were conducted using 16 tests for two problems to assess the efficiency of the suggested algorithm. Furthermore, the execution of the suggested algorithm with that of other meta-heuristic methods was contrasted. The outcome revealed that the performance dimensions of the suggested algorithm overrated those of other techniques.

Organizing sports matches with a hybrid monkey search algorithm

This academic piece of the paper illustrates an approach of organizing sports matches to be as a tool of sports schedule maker via a proposed hybrid Monkey search algorithm by doubles elimination tournament. Input are a set of teams represented by monkeys. It states that the natural behavior of monkeys and its climbing to obtain (solution) through uphill (climbing), watch-jumping, and somersault process. The parameters in the climb were represented by whether or not sports team won. The distribution of the teams, whether in the upper or the lower half, represented in the watch-jumping by mathematical equations, in addition to representing the variables in somersault process. The consequences behind the suggested algorithm used have tackled steps to reach an optimal schedule for a variety of teams for the same championship. The team cannot play more than two consecutive matches with the condition of starting with a random population of feasible solutions. The performance of the presented algorithm was very well through providing a flexible and easy organization of sports matches without using classic or manual routine. Furthermore, the search space reduced so that can give a guarantee to achieve a globally optimum solution. The software platform was MATLAB m-files.

An Experimental Study of a New Keypoint Matching Algorithm for Automatic Point Cloud Registration

Light detection and ranging (LiDAR) data systems mounted on a moving or stationary platform provide 3D point cloud data for various purposes. In applications where the interested area or object needs to be measured twice or more with a shift, precise registration of the obtained point clouds is crucial for generating a healthy model with the combination of the overlapped point clouds. Automatic registration of the point clouds in the common coordinate system using the iterative closest point (ICP) algorithm or its variants is one of the frequently applied methods in the literature, and a number of studies focus on improving the registration process algorithms for achieving better results. This study proposed and tested a different approach for automatic keypoint detecting and matching in coarse registration of the point clouds before fine registration using the ICP algorithm. In the suggested algorithm, the keypoints were matched considering their geometrical relations expressed by means of the angles and distances among them. Hence, contributing the quality improvement of the 3D model obtained through the fine registration process, which is carried out using the ICP method, was our aim. The performance of the new algorithm was assessed using the root mean square error (RMSE) of the 3D transformation in the rough alignment stage as well as a-prior and a-posterior RMSE values of the ICP algorithm. The new algorithm was also compared with the point feature histogram (PFH) descriptor and matching algorithm, accompanying two commonly used detectors. In result of the comparisons, the superiorities and disadvantages of the suggested algorithm were discussed. The measurements for the datasets employed in the experiments were carried out using scanned data of a 6 cm × 6 cm × 10 cm Aristotle sculpture in the laboratory environment, and a building facade in the outdoor as well as using the publically available Stanford bunny sculpture data. In each case study, the proposed algorithm provided satisfying performance with superior accuracy and less iteration number in the ICP process compared to the other coarse registration methods. From the point clouds where coarse registration has been made with the proposed method, the fine registration accuracies in terms of RMSE values with ICP iterations are calculated as ~0.29 cm for Aristotle and Stanford bunny sculptures, ~2.0 cm for the building facade, respectively.

AN APPROACH TO ESTIMATING THE RATE OF ORGANIC DEPOSIT FORMATION IN A HOLLOW ROD STRING AND SELECTION OF METHODS FOR DEPOSIT PREVENTION

Background. There is currently a lack of a methodology that can enable highly-precise determinations of rates of asphaltene deposit (AD) formations in case of dual operation of two oil reservoirs via a single multi-zone oil-producing well using small-bore hollow rods as part of downhole pumping equipment. This methodology aims to minimize the costs of oil and gas companies for servicing such oil wells and preventing their failure. Aims. Creating a methodology aimed at accurate quantitative estimations of the organic deposit formation rates at the inner part of the hollow rod strings. Methods. Calculations of temperature distributions along the hollow rod string inner surface; graphic presentations of the calculated data; laboratory tests using a Cold Finger unit for the selected sections of the hollow rod strings and the graphic presentations of the results. Results and Discussion. The suggested algorithm was field-tested at a target multi-zone oil-producing well of Pavlovka oil field in Perm Krai of the Russian Federation. Using the suggested algorithm, a variation in organic deposit formation rates along the hollow rod string length was evaluated, and the depth of the maximum deposit formation rate was determined. To prevent the deposits in question along the hollow rod string at a target oil-producing well of Pavlovka oil field, laboratory tests were conducted to determine the efficiency of employing the chemical technology, i.e., the use of AD inhibitors, as well as a technology for the removal of the formed deposits using AD solvents. Conclusions. The proposed algorithm is more accurate and requires less time and money compared to existing algorithms. It enables the most effective evaluation of the formation depth of the organic deposits and the intensity at these marks. When evaluating the laboratory studies results, it can be noted that the use of the considered technologies to eliminate organic deposits is highly effective and can be used for this purpose.

A Tamper-Resistant Algorithm Using Blockchain for the Digital Tachograph

A tachograph in a vehicle records the vehicle operating conditions, such as speed, distance, brake operation conditions, acceleration, GPS information, etc., in intervals of one second. For accidents, the tachograph records information, such as the acceleration and direction of a vehicle traveling in intervals of 1/100 s for 10 s before and after the accident occurs as collision data. A vehicle equipped with a tachograph is obliged to upload operation data to administrative organizations periodically via other auxiliary storage devices like a USB attached external memory or online wireless communication. If there is a problem with the recorded contents, data may be at risk of being tampered with during the uploading process. This research proposed tamper-resistant technology based on blockchain for data in online and offline environments. The suggested algorithm proposed a new data recording mechanism that operates in low-level hardware of digital tachographs for tamper-resistance in light blockchains and on/offline situations. The average encoding time of the proposed light blockchain was 1.85 ms/Mb, while the average decoding time was 1.65 ms/Mb. With the outliers in statistical tests removed, the estimated average encoding and decoding time was 1.32 ms/Mb and 1.29 ms/Mb, respectively, and the tamper verification test detected all the tampered data.

A Multiswarm Intelligence Algorithm for Expensive Bound Constrained Optimization Problems

Constrained optimization plays an important role in many decision-making problems and various real-world applications. In the last two decades, various evolutionary algorithms (EAs) were developed and still are developing under the umbrella of evolutionary computation. In general, EAs are mainly categorized into nature-inspired and swarm-intelligence- (SI-) based paradigms. All these developed algorithms have some merits and also demerits. Particle swarm optimization (PSO), firefly algorithm, ant colony optimization (ACO), and bat algorithm (BA) have gained much popularity and they have successfully tackled various test suites of benchmark functions and real-world problems. These SI-based algorithms follow the social and interactive principles to perform their search process while approximating solution for the given problems. In this paper, a multiswarm-intelligence-based algorithm (MSIA) is developed to cope with bound constrained functions. The suggested algorithm integrates the SI-based algorithms to evolve population and handle exploration versus exploitation issues. Thirty bound constrained benchmark functions are used to evaluate the performance of the proposed algorithm. The test suite of benchmark function is recently designed for the special session of EAs competition in IEEE Congress on Evolutionary Computation (IEEE-CEC′13). The suggested algorithm has approximated promising solutions with good convergence and diversity maintenance for most of the used bound constrained single optimization problems.

Iterative Solutions for Solving Variational Inequalities and Fixed-Point Problems

In this paper, we are interested in variational inequalities and fixed-point problems in Hilbert spaces. We present an iterative algorithm for finding a solution of the studied variational inequalities and fixed-point problems. We show the strong convergence of the suggested algorithm.