Testbed System Research Articles

A Holistic System Lifecycle Engineering Approach – Closing the Loop between System Architecture and Digital Twins

This contribution introduces an approach for the optimization of smart products and systems in the early development phases through a Closed-Loop Systems Engineering approach. This approach – holistic in terms of considering the overall system and its usage context, interdisciplinary, overreaching multiple lifecycle phases, and supported methodologically as well as tool-wise – combines aspects from both Model-Based Systems Engineering and Product resp. System Lifecycle Management to optimize the system by using advanced verification and validation methods and techniques, in particular Model-, Twin- and System-in-the-Loop, and seamless feedback of product usage data to the early development phase. This approach has been prototypically applied at the example of a test bed of an autonomous construction area system of systems.

ТЕРАГЕРЦОВІ ТЕХНОЛОГІЇ В ТЕЛЕКОМУНІКАЦІЙНИХ СИСТЕМАХ. ЧАСТИНА 2. ДОСЛІДЖЕННЯ ТА МОДЕЛЮВАННЯ ПЕРЕДАВАННЯ ТЕЛЕВІЗІЙНИХ СИГНАЛІВ СТАНДАРТУ DVB-C І ІМПУЛЬСНОГО НАДШИРОКОСМУГОВОГО СИГНАЛУ РАДІОЛІНІЄЮ ТЕРАГЕРЦОВОГО ДІАПАЗОНУ

The laboratory testbed of a digital simplex radio-relay system of the terahertz range has been studied for the first time in practical terms. It consists of the receiver and transmitter parts of 130÷134 GHz frequency range and a digital modem with a channel data transmission of up to 1200 Mbps for a communication point-to-point distance under normal conditions within 1 km. It is shown that the proposed telecommunication system, which implements the concept of the creation of software-defined radio systems based on Wi-Fi technology, can be highly productive in the next generation mobile communication networks providing the appropriate transmission speeds, reliability, and security. It is studied the parameters of multichannel digital TV signal DVB-C standard when it is transmitted through the testbed of the transmitter and receiver parts of 130 GHz band. The results of the research showed that the application of lower part of terahertz frequency band (130 GHz) with a bandwidth of 24 MHz allows the transmission of three DVB-C television broadcasting channels with a total transport speed of 125 Mbit/s with a high subjective quality of TV programs. The results of the simulation of impulse ultrawideband (IR-UWB) signal transmission by the wireless link of terahertz band are presented. The results of researches of changes of IR-UWB Gaussian monocycle in the transmitter part and its reception by the receiver part of 130.4÷131.5 GHz terahertz band are presented for the first time. On the basis of the results of the research, the requirements for parameters of terahertz wireless link are formulated to ensure acceptable quality of ultrawideband impulse signals receiving. Development of the transmitter and receiver parts of radio relay system of the terahertz range has no direct current analogs in Ukraine. It can provide a significant breakthrough in the development of the telecommunications industry. The obtained research results will also contribute to the development of telecommunications-related industries, in particular: radio astronomy, inter-satellite communication, radar systems, medicine, etc.

Quaternion-based Robust Trajectory Tracking Control of a Quadrotor Hover System

This paper presents a robust nonlinear output feedback control method that achieves three degree of freedom (3-DOF) attitude trajectory tracking of a hover system test bed. The proposed control method formally incorporates dynamic model uncertainty in addition to test bed voltage constraints. To reduce the computational requirement in the closed-loop system, constant feedforward estimates of the input-multiplicative parametric uncertainty are utilized in lieu of adaptive parameter estimates. To eliminate the need for angular rate measurements, the control design employs a bank of dynamic filters, which operates as a velocity estimator in the closed-loop system. A rigorous error system development and Lyapunov-based stability analysis are presented to prove asymptotic 3-DOF attitude trajectory tracking control. Computer simulation and experimental results are also included to illustrate the performance of the attitude control method using the Quanser 3-DOF hover system test bed.

Enhancement of Signal Performance in bidirectional RSE-based CVLC system employing NPM modulation scheme

Abstract Camera-based visible light communication (CVLC) exploiting rolling shutter effect (RSE) is a cost-effective technique that ensures secure data transmission. In this paper, a bidirectional CVLC system is experimentally demonstrated using smartphone/laptop as downlink/uplink transceiver in an experimental prototype testbed. Meanwhile, a Nyquist pre-distorted Manchester (NPM) modulation scheme is proposed and validated in the experimental testbed system. The proposed scheme is based on low-complexity transmitter-side digital signal processing (DSP) techniques, Nyquist shaping and linear pre-distortion, which can be employed for mitigation of the impact of extinction ratio (ER) fluctuation and exposure overlapping in the RSE-based CVLC system. The experimental results show that by using the proposed NPM modulation, the uplink and the downlink can both achieve about 4.8 Kb/s transmission with bit error rate (BER) of below than 3.8e−3. It verifies the effectiveness of the proposed NPM scheme and the corresponding transmitter-side DSP techniques.

Simulation and Test Bed of a Low-Power Digital Excitation System for Industry 4.0

Since modeling and simulation are the two most effective tools that can be used in the design or analysis process, they play a vital role in developing such system. In many cases, they are the only possible means of making a safe engineering decision for a new concept of process for a large-scale system. Elsewhere, they are used as a critical element in the analysis of energy systems or to suggest a method of developing a novel and effective energy system model. Thus, in this study, simulations and test bed experiment were carried out to assess a low-power digital excitation system in order to validate its effectiveness. The excitation systems currently used by most of the power stations in the Republic of Korea were installed during the 1970s or 1980s. Unfortunately, it is difficult to seek technical assistance for them as they depend on foreign technologies, requiring a large sum to be paid when requesting one or more engineers to be dispatched. As such, technical updates have always been made by foreign companies, since it is not easy to make modifications to the system without the help of the original system developer. The technology developed in this study was designed to address such problem. The inability to conduct a test for an actual system can be solved by using a power system analysis program to analyze the characteristics of the controller. The study confirmed the system’s effectiveness, and the Test Bed was proven to be flexible and adequate for the experiment. The proposed excitation system is expected to increase the stability and economic effect of the system by optimizing existing systems. In the future, the authors plan to focus on student education by establishing an education system that allows students to learn about the digital excitation system and its simulation.

SCADA System Testbed for Cybersecurity Research Using Machine Learning Approach

This paper presents the development of a Supervisory Control and Data Acquisition (SCADA) system testbed used for cybersecurity research. The testbed consists of a water storage tank’s control system, which is a stage in the process of water treatment and distribution. Sophisticated cyber-attacks were conducted against the testbed. During the attacks, the network traffic was captured, and features were extracted from the traffic to build a dataset for training and testing different machine learning algorithms. Five traditional machine learning algorithms were trained to detect the attacks: Random Forest, Decision Tree, Logistic Regression, Naïve Bayes and KNN. Then, the trained machine learning models were built and deployed in the network, where new tests were made using online network traffic. The performance obtained during the training and testing of the machine learning models was compared to the performance obtained during the online deployment of these models in the network. The results show the efficiency of the machine learning models in detecting the attacks in real time. The testbed provides a good understanding of the effects and consequences of attacks on real SCADA environments.

Practical Multichannel SAR Imaging in the Maritime Environment

The U.S. Naval Research Laboratory (NRL) recently developed an X-band airborne multichannel synthetic aperture radar (MSAR) test bed system that consists of 32 along-track phase centers. This system was deployed in September 2014 and again in October 2015 to perform extensive and systematic data collections on a variety of land and maritime scenes under different environmental conditions. This paper presents a detailed experimental analysis of imaging in the maritime domain using data captured by the NRL MSAR system. After presenting some of the important details of our NRL MSAR system, we demonstrate velocity-based imaging of a variety of moving backscatter sources including ships and shoaling ocean waves. Our analysis is based on the velocity SAR (VSAR) technique, which was originally conceived by Friedlander and Porat. Practical application of this algorithm in the maritime domain requires a number of pre- and postprocessing stages, which are described here in detail. Our results are then benchmarked against the traditional along-track interferometry, where it is demonstrated that VSAR processing is better able to correctly compensate motion-induced distortion.

Study on the Fast Air Heating Method for the Testbed of the Environmental Control System of the Aircraft

In this paper, the necessity of studying the dynamic performance of the control system was firstly discussed. Through analysing the technical difficulties of the dynamic performance of the thermodynamic testbed, it was found that the most important problem to be solved was to simulate the actual working process of the engine and guarantee the test piece has a sufficiently high supply air temperature to meet the requirements of rapid air temperature rise. Through investigating the method of fast heating, the hot and cold blending method was proposed to realize the rapid response of the temperature. Through the switching of different air supply lines, the process of rapid temperature rising can be achieved.

Study on the Simulink Model for the Testbed of the Environmental Control System of the Aircraft

The rapid rise in temperature and pressure and the Switching of high pressure and medium pressure state of the thermal dynamic testbed is realized by the switch between the two channels of gas supply. The dynamic performance depends mainly on the travel time of the switch valve. We simulate the class step change, which basically meet the needs of the dynamic test of the environmental control system. The dynamic rising temperature and pressure of the testbed depends mainly on the mixing of the cold and hot air and the adjustment of the regulating valve. It cannot be directly evaluated that how many dynamic performance indicators can be achieved. The MATLAB/Simulink modelling software is used to build the thermal dynamic test platform system and control model. And we use this dynamic simulation technique to analyse the time of fast response.

Mutual information algorithms for optimal attribute selection in data driven partitions of databases

Clustering algorithms like k-means, BIRCH, CLARANS and DBSCAN are designed to be scalable and they are developed to discover clusters in the full dimensional space of a database. Nevertheless their characteristics depend upon the size of the database. A database/data warehouse may store terabytes of data. Complex data analysis (mining) may take a very long time to run on the complex dataset. One has to obtain a reduced representation of the dataset that is much smaller in volume—but yet produces the same or almost the same analytical results—in order to accelerate information processing. Reduced representations yield simplified models that are easier to interpret, avoid the curse of dimensionality and enhance generalization by reducing overfitting. Data reduction methods include data cube aggregation, attribute subset selection, fitting data into models, dimensionality reduction, hierarchies as well as other approaches. On the other hand, data-dependent partitions—like the Gessaman’s partition and tree-quantization partition—allow for processing different partitions of a dataset separately. Hence parallel processing may be used as an option for big data. Online analytical processing is a practical approach that deals with multi-dimensional queries in DB management. Feature selection is considered as a specific case of a more general paradigm which is called Structure Learning in cases of an outcome associated to a set of attributes. Feature selection aims at selecting a minimum set of features such that the probability distribution of different classes given the values of those features is as close as possible to the original distribution given the values of all features. A mutual information approach based upon representing complex datasets in DB as a minimal set of coherent attribute sets of reduced dimensions is herein proposed. The novelty of the proposed approach consists of employing piecewise analysis of compact clusters in order to increase overall Shannon’s mutual information-entropy as a variant to conventional Classification and Regression Trees. Numerical data regarding a test-bed system for anomaly detection are provided in order to illustrate the aforementioned approach.

Optimizing a Test Bed System to Assess Human Respiratory Safety After Exposure to Chemical and Particle Aerosolization

Abstract In the last decade, there has been a movement within environmental health and toxicology research to progressively phase out animal testing and implement more rigorous and validated cell c...

Incremental parallel computing for continuous queries in dynamic graphs using a transactional model

SummaryIn dynamically evolving graphs, one may be interested in continuously observing certain properties of the graph. One approach for continuous monitoring is to re‐execute the graph analytics program on the entire graph after it is updated. However, this approach can lead to high computation cost and latency in case of large graphs. An alternate approach, which we present in this paper, is to execute the analytics program only initially and then perform incremental computations for supporting continuous queries as the graph is modified. The goal of our work is to develop incremental parallel computing techniques to continuously monitor a graph as it is updated to check for the properties of interest. We present the results of our investigation of utilizing a transactional model of parallel programming for supporting continuous queries on dynamic and evolving graphs. In our model, the graph updates are performed as transactions, which trigger the execution of a set of transactional tasks to perform incremental computations. In our testbed system, the graph data is stored in the RAM of cluster nodes, and continuous queries involve the parallel execution of transactional tasks on the cluster nodes. Using a set of graph problems, we illustrate this approach and evaluate its performance.

Bright‐Dark Rogue Waves

AbstractDuring the last two decades, revealing mechanisms of origin waves with anomalous amplitude (rogue waves) have been in the focus of researchers from different fields ranging from oceanography to laser physics. Mode‐locked lasers, as a test bed system, provide a unique opportunity to collect more data on rogue waves in the form of random pulses (soliton rain) and to clarify the mechanisms of rogue‐wave emergence caused by soliton–soliton and soliton–dispersive wave interactions. Here, for the first time, for an Er‐doped mode‐locked laser, a new type of vector rogue waves is demonstrated experimentally and theoretically, which is driven by desynchronization of the orthogonal linear states of polarization, so leading to output power oscillations in the form of anomalous spikes‐dips (bright‐dark rogue waves). The results can pave the way to unlocking the universal nature of the origin of rogue waves and thus can be of interest to the broad scientific community.

Current polarity-dependent manipulation of antiferromagnetic domains.

Antiferromagnets have several favourable properties as active elements in spintronic devices, including ultra-fast dynamics, zero stray fields and insensitivity to external magnetic fields 1 . Tetragonal CuMnAs is a testbed system in which the antiferromagnetic order parameter can be switched reversibly at ambient conditions using electrical currents 2 . In previous experiments, orthogonal in-plane current pulses were used to induce 90° rotations of antiferromagnetic domains and demonstrate the operation of all-electrical memory bits in a multi-terminal geometry 3 . Here, we demonstrate that antiferromagnetic domain walls can be manipulated to realize stable and reproducible domain changes using only two electrical contacts. This is achieved by using the polarity of the current to switch the sign of the current-induced effective field acting on the antiferromagnetic sublattices. The resulting reversible domain and domain wall reconfigurations are imaged using X-ray magnetic linear dichroism microscopy, and can also be detected electrically. Switching by domain-wall motion can occur at much lower current densities than those needed for coherent domain switching.

On the effects of spreading sequence pairs over MIMO-STS systems

Previous studies have found that the Multiple Access Interference (MAI) effect is strongly associated with which sequence pairs are spread over Multiple-Input Multiple-Output Space-Time Spreading (MIMO-STS) systems. An improved method of determining which sequence pairs are to be spread is proposed. The choice of these pairs from the selected spreading code families results in a number of ways to mitigate the MAI effects. A Software Defined Radio (SDR) test bed system has been developed to evaluate the selected spreading sequences, in an attempt to mitigate the MAI effects over 2 × 1 MIMO-STS systems. The SDR test bed results reveal that, for a number of the spreading sequence families, improved transmission properties for asynchronous transmission can be achieved.

Dynamic IEEE Test Systems for Transient Analysis

Transient stability analysis is performed to assess the power system's condition after a severe contingency and is carried out using simulations. To adequately assess the system's transient stability, the correct dynamic models for the machines (i.e., generators, condensers, and motors) along with their dynamic parameters must be defined. The IEEE test systems contain the data required for steady-state studies. However, neither the dynamic model of the machines nor their specific parameters have been established for transient studies. As a result, there is a demand for test bed systems suitable for transient analysis. This paper defines dynamic machine models along with their parameters for each IEEE test bed system, thus producing full dynamic models for all test systems. It is important to mention that the parameters of the proposed dynamic models are based on typical data. The test systems are subjected to large disturbances, and a case study for each test system, which examines the frequency, angle, and voltage stability, is presented. Furthermore, the proposed dynamic IEEE test systems, implemented in PowerWorld, are available online.

Security Technology of Wireless Sensor Internet of Things Based on Data Fusion

In order to prove the effect of data fusion technology in the Internet of things, a wireless sensor Internet of things security technology based on data fusion is designed, and the impact of data fusion in the field of communication technology is studied. Therefore, two security fusion algorithms are designed on the basis of analyzing and comparing the advantages and disadvantages of various security fusion algorithms, namely, data security fusion algorithm EDCSDA and approximate fusion algorithm PADSA. By analyzing the probability distribution model of the data collected by the nodes, the disturbance data is superimposed on the original data to hide the effect of the original data. A test bed system for perception layer of the Internet of things is designed and implemented. The test results prove the feasibility of the two algorithms. Meanwhile, it shows that the two algorithms can reduce the transmission overhead of the network while guaranteeing the security. Based on the above finding, it is concluded that data fusion technology is very effective for improving network efficiency and prolonging the network life cycle as one of the key technologies in the perception layer of Internet of things.

Planar interpolation with extreme deformation, topology change and dynamics

We present a mesh-based, interpolatory method for interactively creating artist-directed inbetweens from arbitrary sets of 2D drawing shapes without rigging. To enable artistic freedom of expression we remove prior restrictions on the range of possible changes between shapes; we support interpolation with extreme deformation and unrestricted topology change. To do this, we extend discrete variational interpolation by introducing a consistent multimesh structure over drawings, a Comesh Optimization algorithm that optimizes our multimesh for both intra- and inter-mesh quality, and a new shape-space energy that efficiently supports arbitrary changes and can prevent artwork overlap when desired. Our multimesh encodes specified correspondences that guide interpolation paths between shapes. With these correspondences, an efficient local-global minimization of our energy interpolates n-way between drawing shapes to create inbetweens. Our Comesh Optimization enables artifact-free minimization by building consistent meshes across drawings that improve both the quality of per-mesh energy discretization and inter-mesh mapping distortions, while guaranteeing a single, compatible triangulation. We implement our method in a test-bed interpolation system that allows interactive creation and editing of animations from sparse key drawings with arbitrary topology and shape change.

Utility-based resource management in an oversubscribed energy-constrained heterogeneous environment executing parallel applications

Abstract The worth of completing parallel tasks is modeled using utility functions, which monotonically-decrease with time and represent the importance and urgency of a task. These functions define the utility earned by a task at the time of its completion. The performance of a computing system is measured as the total utility earned by all completed tasks over some interval of time (e.g., 24 h). We have designed, analyzed, and compared the performance of a set of heuristic techniques to maximize system performance when scheduling dynamically arriving parallel tasks onto a high performance computing (HPC) system that is oversubscribed and energy constrained. We consider six utility-aware heuristics and four existing heuristics for comparison. A new concept of temporary place-holders is compared with scheduling using permanent reservations. We also present a novel energy filtering technique that constrains the maximum energy-per-resource used by each task. We conducted a simulation study to evaluate the performance of these heuristics and techniques in multiple energy-constrained oversubscribed HPC environments. We conduct an experiment with a subset of the heuristics on a physical testbed system for one scheduling scenario. We demonstrate that our proposed utility-aware resource management heuristics are able to significantly outperform existing techniques.

Test Bed Calibration by Trend Analysis for Reliability of a Turboshaft Engine Performance

Aero-engine test bed is the most vital test bench or test equipment for assessing the performance of any aero-engine after production, repair or overhaul as per the performance specification. Aero-engine test bed thus requires periodic calibration as a part of any quality control checks of engine passing out as per the acceptance test procedure laid down for the engine. Periodic aero-engine test bed calibration includes not only calibrating the various sensors used in the test bed system independently but also subjecting the test bed as a whole for calibration with a master engine. While calibration periodicity of the test bed sensors is generally one year or so, test bed calibration as a whole is carried out once in two years. Calibration of test bed using a master engine is very expensive and sometimes not feasible due to non-availability of such engines belonging to early generation of fighter aircrafts. This paper presents a novel concept for calibrating engine test bed using trend analysis. It is mainly based on the performance data of engine acceptance tests carried out over a considerable period of time. This concept completely avoids requirement of a master engine and thus saves enormous effort in terms of cost and man-hours. The concept evolved has been used for calibrating a typical vintage test bed as the proof for validation and found the results comparable with the present trending pattern followed by other engine houses.