Limited Power Research Articles

Latch: Enabling large-scale automated testing on constrained systems

Testing is an essential part of the software development cycle. Unfortunately, testing on constrained devices is currently very challenging. First, the limited memory of constrained devices severely restricts the size of test suites. Second, the limited processing power causes test suites to execute slowly, preventing a fast feedback loop. Third, when the constrained device becomes unresponsive, it is impossible to distinguish between the test failing or taking very long, forcing the developer to work with timeouts. Unfortunately, timeouts can cause tests to be flaky, i.e., have unpredictable outcomes independent of code changes. Given these problems, most IoT developers rely on laborious manual testing.In this paper, we propose the novel testing framework Latch (Large-scale Automated Testing on Constrained Hardware) to overcome the three main challenges of running large test suites on constrained hardware, as well as automate manual testing scenarios through a novel testing methodology based on debugger-like operations—we call this new testing approach managed testing.The core idea of Latch is to enable testing on constrained devices without those devices maintaining the whole test suite in memory. Therefore, programmers script and run tests on a workstation which then step-wise instructs the constrained device to execute each test, thereby overcoming the memory constraints. Our testing framework further allows developers to mark tests as depending on other tests. This way, Latch can skip tests that depend on previously failing tests resulting in a faster feedback loop. Finally, Latch addresses the issue of timeouts and flaky tests by including an analysis mode that provides feedback on timeouts and the flakiness of tests.To illustrate the expressiveness of Latch, we present testing scenarios representing unit testing, integration testing, and end-to-end testing. We evaluate the performance of Latch by testing a virtual machine against the WebAssembly specification, with a large test suite consisting of 10,213 tests running on an ESP32 microcontroller. Our experience shows that the testing framework is expressive, reliable and reasonably fast, making it suitable to run large test suites on constrained devices. Furthermore, the debugger-like operations enable to closely mimic manual testing.

Performance Study of Object Tracking with Multiple Kalman Filters in Autonomous Driving Systems

Object tracking is an important and central aspect of autonomous driving, as it underlies the obstacle detection and avoidance systems of any type of autonomous vehicles. A widely used method for tracking is based on Kalman filters, both for linear and non-linear cases, with different computational burden. Unfortunately, object tracking algorithms are computationally intensive, and they may not easily meet the efficiency and responsiveness requirements of real-time applications such as autonomous driving. This issue motivates ad-hoc investigations to speed up the computation and make Kalman filtering available even within limited computational power. This paper carry out a performance evaluation of a Kalman filter based object tracking system taken from a real tramway use-case, and aims at improving its performance efficiency by leveraging parallelization. In particular, this work analyzes the possibilities of execution parallelization on multi-core processors, proposing a target-specific optimization approach and comparing the obtained results, then summing them in general lessons learned. Our technique achieves up to 80% reduction of single frame processing time in the most crowded cases.

Secondary cluster head based SEP in heterogeneous WSNs for IoT applications

AbstractA wireless sensor network (WSN) consists of specialized sensor nodes that perform sensing services for Internet of Things devices with limited battery power. As the replacement or recharging of batteries is not possible, energy consumption becomes the most important design issue in WSNs. The energy‐efficient routing protocol gets the most priority in such energy‐constrained networks. The utilization of clustering‐based routing protocols like stable election protocol (SEP) has gained much attention as the network's lifetime is significantly improved due to the clustering of sensor nodes. Moreover, the inclusion of a secondary CH (SCH) is beneficial when the member node with the most remaining energy performs data aggregation and reduces the energy burden of the CH. This article characterizes SEP and Prolong SEP (P‐SEP) protocols and then extends them by incorporating SCH, which ensures balanced energy consumption. The performance of the proposed Extended SEP and Extended P‐SEP protocols has been analysed regarding stability period, network lifetime, energy usage and throughput. The simulation results demonstrate that the proposed protocols outperform state‐of‐the‐art protocols like P‐SEP, Modified SEP (M‐SEP) and SEP. In particular, the stability period of Extended SEP and Extended P‐SEP has improved up to 42% and 89%, respectively, compared to M‐SEP.

Evaluating the safety of the redesigned shafting system following the propeller redesign aimed at enhancing CII and EEXI

In July 2023, the International Maritime Organization (IMO) set a target to achieve net-zero greenhouse gas emissions by 2050, introducing key measures such as the Energy Efficiency Design Index (EEDI), the Energy Efficiency Existing Ship Index (EEXI), and the Carbon Intensity Indicator (CII). The maritime industry explored adaptations, including engine de-rating, energy-efficient technologies, and propeller modifications, and beyond. This study assessed the safety implication of a redesigned shafting system, resulting in a propeller redesign to enhance the CII and EEXI on a 6500 TEU container ship built in 2006. Through an analysis of annual output per TEU from 2000 to 2015, the study focused on container ships built from 2005 to 2007 with high-output engines (9.4–9.5 kW/TEU). After selecting a sample ship, the study determined engine power limits according to the EEXI regulations and assessed their impact on the CII. Subsequently, the study redesigned the shafting system, performing torsional vibration calculations and shaft alignment analyses to ensure the safety of the modified system. While an enhanced CII rating was predicted, the tightening CII regulations imply this benefit may be short-lived, lasting approximately two years. Thus, additional measures are essential to prolong the improved CII rating.

Mathematical and Experimental Simulation of Operating Modes of Capillary Emitter of Electrostatic Colloidal Microthruster

This work experimentally and theoretically analyzes the dynamics of the process of ion emission from a capillary emitter filled with an ionic liquid as a working fluid. Such emitters can be used in the energy system of low-mass satellites as a source of jet propulsion. The dependence of the thrust of a micromotor on the electrical power supplied to it was experimentally studied, which made it possible to determine the most efficient operating modes of the microthruster. This is of interest from the point of view of increasing the energy efficiency of the latter in conditions of limited power availability of low-mass satellites. It was found that the characteristic “electric field voltage – emitter thrust” is non-monotonic with a pronounced maximum, which imposes restrictions on the magnitude of the electric field in the emitter. To explain the limit of emission intensity, a diffusion-convective model of ion movement inside the capillary was constructed. The main idea of the proposed model is the assumption that the intensity of ion emission is determined by their concentration at the outlet of the capillary, and the velocity of the emitted ions is higher than the velocity of flow of the ionic liquid in the capillary as a continuous medium. Moreover, the acceleration of ions at the outlet of the emitter increases nonlinearly with increasing external forces. The decrease in the concentration of ions as they are emitted must be compensated by their diffusion inside the capillary and convective flows, the velocity of which is limited. The constructed system of equations is analyzed numerically. For the system of Navier – Stokes equations, the projection method proposed by Chorin is applied. Based on the known velocity field, density, and concentration distribution, a time step is taken for the equations of motion. Then, taking into account the found velocity, a time step is taken for the convective diffusion equations and the density field is recalculated. The created code made it possible to confirm the possibility of the existence of a maximum mass flow rate of ions, i.e., micromotor thrust, which is in qualitative agreement with the experimental data. The main factor on which the magnitude of the maximum and its position depend is the degree of nonlinearity of the coefficient responsible for the acceleration of ions at the outlet of the capillary.

Impulsive Response Analysis of Financial Markets in QUAD Economies: A VAR Modelling Approach

Financial market integration remains a key focus in academic finance, especially given how crucial it is to portfolio diversification. The purpose of this research is to investigate a crucial yet underexplored aspect like the cointegration of economies with formal or unofficial military ties, focusing on countries within the Quad strategic forum—India, Japan, Australia, and the United States. The daily closing values of benchmark stock market indices of Quad economies viz. Nikkie 225 for Japan, S&P ASX 200 for Australia, NASDAQ composite for the United States, and S&P Sensex for India were considered. Unit root tests, Johansen Cointegration tests, VAR (Vector Autoregressive) model, and the Granger Causality statistics are computed for data analysis. Additionally, the Impulse response function and variance decomposition are computed for better financial market predictions. The result reveals intriguing dynamics: while the Indian stock market initially responds positively to shocks in the Australian market, this effect diminishes over time. Also, movements in the Australian and United States stock markets significantly contribute to predicting fluctuations in the Indian market, contrasting with the limited predictive power of the Japanese stock market. These findings carry significant practical implications for international investors, offering valuable guidance for optimizing portfolio diversification strategies amidst geopolitical and economic complexities. This paper contributes to academic literature by offering empirical insights into the short-term dynamics and causal relationships of Quad countries’ stock markets, setting a foundation for future studies on long-term trends and market responses to external factors.

Influence of Bi3+ ions on structural, morphology, elemental, vibrational, optical, magnetic, NLO and optical limiting properties of lanthanum ferrites nanoparticles

Nanoparticles of LaFe1-xBixO3 were successfully synthesized through the microwave combustion process (MCP) employing l-alanine as the fuel source. XRD and FT-IR analyses conclusively confirmed the orthorhombic structure of lanthanum ferrite, with the mean crystallite size varying between 56.32 and 25.43 nm. The optical energy gap value, calculated from UV–vis spectra, fell within the range of 1.84 to 2.49 eV. EDX analyses verified the presence of Bi, La, Fe, and O elements. Furthermore, FE-SEM images exhibited the nanoparticles' distinctive aggregated spherical morphology. Notably, VSM analysis showcased the robust diamagnetic behavior of LaFe1-xBixO3 nanoparticles. In photoluminescence's spectra, the samples underwent excitation with a wavelength of 315 nm. The values of Hc (coercivity) and Mr (remanence) fell within the range of 121.98 to 332.39 Oe and 0.1592 to 0.0907 emu/g for LaFe1-xBixO3 respectively. Z-scan experiments yielded values for the nonlinear susceptibility, index of nonlinear refraction, and coefficient of nonlinear absorption. The findings from optical limiting studies serve as additional verification, underscoring the suitability of these materials as promising options for integration into devices, including optical switches and optical power limiters.

Microwave plasma interaction in a printed transmission line for a power limiting application: from surface-wave-sustained to leaky-wave-sustained discharge

The coupling between a microwave signal and a plasma discharge in a suspended microstrip transmission line is analytically studied. Maxwell’s equations are solved in a 2D approximation to get the expressions of the electromagnetic field. The wave propagation in the guiding structure is first explored without plasma, and for several modes and frequencies. A unified characterization of the three different modes that can propagate at the interface between two dielectric media, namely the leaky waves, the pseudo-surface wave and the pure surface wave, is given in terms of of both wave vectors and electromagnetic field magnitude distribution. This analyze allow to conclude that the fundamental mode in this case is a pseudo-surface wave. Thereafter, we focus on the microwave propagation with a uniform plasma inside the guiding structure. In the non collisional limit, it appears that the plasma discharge is sustained by the so-called pure surface wave, whereas in the collisional limit, a leaky wave propagates along the plasma column. Finally, a non-uniform density profile is taken into account in the calculation. The numerical results obtained from the self-consistent simulation of the microwave-plasma coupling, in a previous work, are thus analyzed with the aid of the analytical formulas to identify the microwave coupling involved in our plasma-based microwave power limiter. The computed propagation constant from numerical data confirmed the type of coupling exhibited for a uniform electron density. Furthermore, we highlight the role of the dielectric slab, from which electromagnetic power transfer occurs into the plasma discharge.

Functional Performance and Tendon Morphology After Operative or Nonoperative Treatment of Achilles Tendon Ruptures.

While controversy remains as to the relative benefit of operative (OM) versus non-operative management (NOM) of Achilles tendon (AT) ruptures (ATR), few studies have examined the effect on high impact maneuvers such as jumping and hopping. The purpose of this study was to determine if functional performance including strength, jumping, and hopping outcomes differed between OM and NOM of acute ATR. The secondary objective was to assess the degree of association between AT morphology and performance outcomes. Retrospective cohort with a single prospective evaluation. All patients were treated at an institutional secondary care center. Eligible participants (n=12 OM; 12 NOM) who were treated with OM or NOM of ATR within three weeks of injury were evaluated a minimum 20 months following ATR. AT length, thickness and gastrocnemius muscle thickness were assessed with B-mode ultrasound. Isokinetic plantar flexor strength, hop tests and countermovement and drop jumps were completed. Two-way ANOVAS were completed on all tests with unilateral values, independent t-tests were used for bilateral outcomes, and linear regressions were completed to assess the relationship between normalized AT length and performance. Affected limb AT was elongated and thickened (p\<0.01), gastrocnemius was atrophied (p\< 0.01) and angle-specific plantar flexor torque was reduced at 120°/s when measured at 20° plantar flexion (p = 0.028). Single leg drop vertical jump was higher in OM (p = 0.015) with no difference for hop and jump tests. AT length was related to plantar flexor torque but had no relationship with hopping performance. Hop test performance was maintained despite plantarflexion weakness, gastrocnemius atrophy, and AT elongation. This may be the result of compensatory movement patterns. AT length holds limited explanatory power in plantar flexor strength, although this relationship should be evaluated further. Level III.

Association of mesenteric volvulus in police working dogs with and without a prior prophylactic laparoscopic gastropexy.

To evaluate the association of mesenteric volvulus (MV) in New York Police Department police working dogs (PWDs) with and without a prior prophylactic laparoscopic gastropexy (PLG). 370 PWDs (82 with and 288 without PLG). Medical records and surgery and radiology reports were reviewed from 2012 to 2022. Signalment, pertinent history (medical and surgical), gastropexy status, temperament, and training type were recorded. Statistical analysis was used to identify the relationship between prophylactic gastropexy and MV within the patient population. 3 cases of mesenteric volvulus were noted in this patient population. Two (2.4%) of the 82 PWDs that had undergone prophylactic laparoscopic gastropexy developed MV, whereas 1 (0.3%) of the 288 PWDs that had not undergone a gastropexy procedure developed MV. Police working dogs with PLG were estimated to be at 7.2 times greater odds of MV (point estimate OR, 7.18; 95% CI, 0.642 to 80.143); however, the low incidence of MV in this population limited statistical power, and thus this effect did not achieve statistical significance. Evaluation of MV incidence in additional populations of working dogs will allow greater precision in the point estimate. Prophylactic gastropexy may be associated with an increased risk for MV. However, patients without prophylactic gastropexy are at risk for gastric dilatation and volvulus, which is more common than MV. Therefore, the authors continue to recommend prophylactic gastropexy to decrease the risk for gastric dilatation and volvulus.

Leveraging Seed Generation for Efficient Hardware Acceleration of Lossless Compression of Remotely Sensed Hyperspectral Images

In the field of satellite imaging, effectively managing the enormous volumes of data from remotely sensed hyperspectral images presents significant challenges due to the limited bandwidth and power available in spaceborne systems. In this paper, we describe the hardware acceleration of a highly efficient lossless compression algorithm, specifically designed for real-time hyperspectral image processing on FPGA platforms. The algorithm utilizes an innovative seed generation method for square root calculations to significantly boost data throughput and reduce energy consumption, both of which represent key factors in satellite operations. When implemented on the Cyclone V FPGA, our method achieves a notable operational throughput of 1598.67 Mega Samples per second (MSps) and maintains a power requirement of under 1 Watt, leading to an efficiency rate of 1829.1 MSps/Watt. A comparative analysis with existing and related state-of-the-art implementations confirms that our system surpasses conventional performance standards, thus facilitating the efficient processing of large-scale hyperspectral datasets, especially in environments where throughput and low energy consumption are prioritized.

Coupled relativistic magnetrons with phase-locked Gaussian radiation pattern

To address the inherent power limitations in a single relativistic magnetron (RM), we explore the feasibility of coupling multiple phase-locked RMs without compromising power conversion efficiencies. Successful phase locking of two coupled A6 RMs, where radiations are axially extracted as TE11 modes, has been achieved. The interaction between the two RMs is facilitated by a well-designed waveguide with a transmission coefficient exceeding 98% in the L-band. In our designed system, as per the particle-in-cell simulation results with a diode voltage of 560 kV, the RMs' peak power of the Gaussian radiation pattern reaches approximately 3.4 GW. The relative phase jitter between these two tubes is effectively controlled within ±1.6%, and the power conversion efficiency reaches up to 48.1%. This study presents a viable approach to enhance the output power of RMs while maintaining phase-locked Gaussian radiation patterns.

Multi-Rotor Wind Turbine Control: Strategies for Pitch Replacement and Mechanical Load Mitigation

This paper presents a two-level control scheme for multi-rotor wind turbines. The first subordinate decentralized controller replaces the active pitch control with oversized generators that achieve the power limitation objective. In combination with this, the second higher-level controller mitigates the mechanical load on the main tower by adjusting the thrust forces acting on the side turbines through coordinated local torque control. The results proved that the decentralized controller managed to replace the pitch control by achieving the same power curve, and the load mitigation controller tended to equate the thrusts on both turbines, which mitigates the mechanical loads on the turbine tower. A high-fidelity QBlade model was developed and showed consistent results to the simplified model in SIMULINK.

Systematic Literature Review of IoT Botnet DDOS Attacks and Evaluation of Detection Techniques.

Internet of Things (IoT) technology has become an inevitable part of our daily lives. With the increase in usage of IoT Devices, manufacturers continuously develop IoT technology. However, the security of IoT devices is left behind in those developments due to cost, size, and computational power limitations. Since these IoT devices are connected to the Internet and have low security levels, one of the main risks of these devices is being compromised by malicious malware and becoming part of IoT botnets. IoT botnets are used for launching different types of large-scale attacks including Distributed Denial-of-Service (DDoS) attacks. These attacks are continuously evolving, and researchers have conducted numerous analyses and studies in this area to narrow security vulnerabilities. This paper systematically reviews the prominent literature on IoT botnet DDoS attacks and detection techniques. Architecture IoT botnet DDoS attacks, evaluations of those attacks, and systematically categorized detection techniques are discussed in detail. The paper presents current threats and detection techniques, and some open research questions are recommended for future studies in this field.

Cometes: Cross-Device Mapping for Energy and Time-Aware Deployment on Edge Infrastructures

As the Internet of Things (IoT) application development falls more on libraries and tools, software developers design applications targeting power-constrained Edge-computing devices. However, not only the Quality-of-Service (QoS) but also energy savings remain major challenges. This article presents Cometes, a complete tool-flow that extends modern SDK tools, assisting developers in selecting resources towards the desired trade-off between execution time and energy consumption, without exceeding the power limitations of the Edge clusters. Cometes runs at application design time, on top of Kubernetes, and exploits cross-device estimation methods as well as traditional multi-objective optimizers to enable efficient resource allocation. The presented solution achieves up to 66% energy savings, up to 50% speed-up and an average improvement of 7%, compared to the placement policy of the lightweight Kubernetes (k3s).

A speed decoupling control method for multi-channel pressure-flow coupling system

Abstract The main engine of construction machinery often involves the compound action of multi-action, such as excavator bucket rod, shovel bucket, and moving arm. Due to the matching relationship between the constant pressure differential valve and main valve, constant power limitation of a pump, load change, and other factors, it will cause the load with low pressure to move first and the load with high pressure to move later. To solve this problem, the existing speed control (or flow control) in the industry generally adopts pre-valve or post-valve compensation load-sensitive systems, positive flow control, negative flow control, constant power control, and so on. The speed control method can solve the coarse flow distribution under multi-load conditions, but is not suitable for working conditions with high precision of flow control or flow distribution, such as speed tracking, trajectory control, etc., and cannot meet the accurate control of flow or speed. In this paper, a speed decoupling control method based on hydraulic factors (such as pressure drop, flow rate, oil temperature, hydraulic pump speed, system pressure, etc.) is proposed. Through accurate modeling and simulation technology, the accuracy of compound action flow control is improved, and the anti-interference energy of the compound action system is enhanced, which lays a foundation for hydraulic speed tracking, displacement tracking, and so on.

Dynamical behaviour and Control of a Magnetic structure, composed by a Shape Memory spring driven by a DC motor with limited power supply to harvesting energy

Dynamical behaviour and Control of a Magnetic structure, composed by a Shape Memory spring driven by a DC motor with limited power supply to harvesting energy

Embedded machine learning-based road conditions and driving behavior monitoring

Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.

Electric vehicle charger energy management by considering several sources and equalizing battery charging

This article proposes a novel energy management structure for electric vehicles, consisting of a supercapacitor and two types of batteries, to improve efficiency and navigable distance. The key features of a suitable energy storage system include high power and energy density, low cost and weight, minimal maintenance, and long life. Although batteries are the primary power storage source in electric vehicles, they have power limitations. Therefore, a high-power-density supercapacitor is added to the battery to create a hybrid energy storage system, reducing stress on the battery and increasing its lifespan. The article presents a new structure for hybrid storage systems based on the existence of a main battery, a replaceable battery, a supercapacitor, and a DC-DC converter. An active charge equalizer circuit for the main battery in standby mode and its control system are also introduced. A control method for dividing power between different sources under different conditions is presented, and the design parameters of the energy storage system are optimized using a genetic algorithm to minimize mass and losses. The performance of the proposed system is evaluated through simulation in MATLAB software and tested in a small-scale laboratory sample. The article also provides a detailed analysis of different working modes, including electric motor acceleration, low-speed mode, high-speed mode, and electric regenerative braking mode. Additionally, a control method for energy management between batteries and supercapacitors is introduced, aiming to increase efficiency. The results show that the proposed hybrid energy storage system can effectively improve the efficiency of electric vehicles.

Dynamic Key Generation Using GWO for IoT System

One well-known technological advancement that significantly impacts many things is the Internet of Things (IoT). These include connectivity, work, healthcare, and the economy. IoT can improve life in many situations, including classrooms and smart cities, through work automation, increased output, and decreased worry. However, cyberattacks and other risks significantly impact intelligent Internet of Things applications. Key generation is essential in information security and the various applications that use a distributed system, networks, or Internet of Things (IoT) systems. Several algorithms have been developed to protect IoT applications from malicious attacks; since IoT devices usually have small memory resources and limited computing and power resources, traditional key generation methods are inappropriate because they require high computational power and memory usage. This paper proposes a method of Dynamic Key Generation Method (DKGM) to overcome the difficulty using a specific chaotic map called the Zaslavskii Map and a swarm intelligent algorithm for optimization called Grey Wolf Optimizer (GWO). DKGM's ability to generate several groups-seed numbers using the Zaslavskii map depends on various initial parameters. GWO selects strong generated numbers depending on the randomness test as a fitness function. Three wolfs GWα, GWβ, and GWΩ, are used to simulate the behavior of a pack of grey wolves when attacking prey. The speed and position of each wolf are updated depending on the best three wolves. Finally, use the sets GWα in the round, GWβ in the subkey, and GWΩ in shifting operations of the Chacha20 hash function. The dynamic procedure was used to improve the high-security analysis of the DKGM approach over earlier methods. Simulations show that the suggested method is preferable for IoT applications.