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This paper will present current efforts on wireless passive surface acoustic wave (SAW) sensor transceiver development for aerospace applications. Our group's SAW sensor work has been sponsored by NASA for the past ten years in efforts to develop wireless sensing for ground base and space exploration in extreme environments. The devices are radiation hard and work from cryogenic to several hundred degrees centigrade with standard device processing. The focus of this paper will be on a synchronous, pulsed correlator transceiver for interrogation of SAW delay-line sensors. The 915-MHz system has a bandwidth of 15 MHz and uses a pulsed noise-generated signal of 1-\(\mu \) s duration. The design principles, system analysis, and receiver measurements are given. The prediction of signal-to-noise ratio versus range is shown for given system parameters. The system development leading to the first testing of SAW liquid level sensors at NASA KSC will be discussed. [ABSTRACT FROM PUBLISHER]

This paper is devoted to the feasibility study of a wireless sensing system, mainly based on passive surface acoustic wave sensors, for remote measurement of temperature aboard space platforms. The use of passive sensors is particularly attractive since they need no battery and are robust in extreme environments, as they contain no active electronic circuits. The main objective of this paper is the complete characterization of the wireless system environment, in order to determine the main fundamental limits of this technology from a communication theory point of view. Preliminary experimental measurements are used for defining the main environment parameters, validating some of the theoretical limit computations, and proving the space application feasibility. [ABSTRACT FROM PUBLISHER]

This paper proposes a real-time fault-tolerant estimation approach for combined sensor fault diagnosis and air data reconstruction. Due to simultaneous influence of winds and latent faults on monitored sensors, it is challenging to address the tradeoff between robustness to wind disturbances and sensitivity to sensor faults. As opposed to conventional fault-tolerant estimators that do not consider any constraints, we propose a constrained fault-tolerant estimator using moving horizon estimation (MHE). By exploiting wind bounds according to the weather or flight conditions, this approach improves fault sensitivity without sacrificing disturbance robustness. This improvement is attributed to active inequality constraints caused by faults, as shown in sensitivity analysis of the formulated MHE problem. The challenge of real-time nonlinear MHE is addressed by adopting an efficient structure-exploiting algorithm within a real-time iteration scheme. In order to facilitate the industrial validation and verification, the algorithm is implemented using an Airbus graphical symbol library to be compliant with the actual flight control computer, and its feasibility of real-time computation has been validated. The simulation results on the RECONFIGURE benchmark, which is a high-fidelity Airbus simulator, over a wide range of the flight envelop show the efficacy of the proposed approach. [ABSTRACT FROM AUTHOR]

In this paper, it is shown how to obtain a low-cost, high-resolution, and fault-robust position sensing system for permanent-magnet synchronous motor drives operating in safety-critical systems, by combining binary Hall-effect sensors with high-frequency signal injection. It is shown that the position error signal obtained via signal injection can be merged easily into the quantization-harmonic-decoupling vector-tracking observer that is used to process the Hall-effect sensor signals. The resulting algorithm provides accurate, high-resolution estimates of speed and position throughout the entire speed range; compared to the state-of-the-art drives using Hall-effect sensors alone, the low-speed performance is greatly improved in healthy conditions and also following position sensor faults. It is envisaged that such a sensing system can be successfully used in applications requiring IEC 61508 SIL 3 or ISO 26262 ASIL D compliance, due to its extremely high mean time to failure and to the very fast recovery of the drive following Hall-effect sensor faults at low speeds. Extensive simulation and experimental results are provided on a 3.7-kW interior permanent-magnet drive. [ABSTRACT FROM AUTHOR]

In this paper, binary Hall-effect sensor faults are investigated in rectangular-current-fed brushless dc (BLDC) drives and a very effective methodology for their detection, identification, and compensation is explored. It is shown that these faults cause erroneous commutation, generally leading to unstable operation. Using a fault detection and identification technique proposed by the authors in a recent paper on low-cost field-oriented drives, it is possible to pinpoint the faulty sensors. In this paper, it is demonstrated that the destabilizing effect of these faults on motion-state estimation can be compensated for in any position and speed estimation algorithm, as long as it is properly readapted. To this end, it is shown how to incorporate such fault-compensation in three state-of-the-art estimation algorithms: 1) the zeroth-order algorithm (ZOA); 2) the hybrid observer (HO); and 3) the vector-tracking observer (VTO). Comparative experimental tests are performed and it is verified that stable operation is achieved with three, two, or only a single Hall-effect sensor functioning correctly. These results show that the classical BLDC drive with three Hall-effect sensors has an inherent double redundancy to position-sensor faults. With the proposed method, this property can be exploited in systems that require very high reliability, such as in aerospace and automotive applications. Redundancy can be increased, using more than three Hall-effect sensors; reduced using two sensors; or eliminated using a single sensor, in ultra low-cost applications where redundancy is not a requirement. [ABSTRACT FROM AUTHOR]

This paper develops an \mathcalL_1 adaptive output feedback controller for a class of underactuated multi-input multi-output (MIMO) systems. The proposed approach is applied as an augmentation of an existing three-loop autopilot. The adaptive scheme is introduced to compensate for the uncertainties and to recover the nominal performance. Stability and performance, both in transient and steady state, are analyzed. Nonlinear simulation results demonstrate the performance of the augmented control system. [ABSTRACT FROM AUTHOR]

Outsourcing, internationalization, and complexity characterize today's aerospace supply chains, making aircraft manufacturers structurally dependent on each other. Despite several complexity-related supply chain issues reported in the literature, aerospace supply chain structure has not been studied due to a lack of empirical data and suitable analytical toolsets for studying system structure. In this paper, we assemble a large-scale empirical data set on the supply network of Airbus and apply the new science of networks to analyze how the industry is structured. Our results show that the system under study is a network, formed by communities connected by hub firms. Hub firms also tend to connect to each other, providing cohesiveness, yet making the network vulnerable to disruptions in them. We also show how network science can be used to identify firms that are operationally critical and that are key to disseminating information. [ABSTRACT FROM PUBLISHER]

This paper presents the modeling, control system design, and experimental results for a prototype lighter-than-air wind energy system being pioneered by Altaeros Energies. This unique design features a horizontal-axis turbine that is elevated to high altitudes through a buoyant shroud, which is tethered to a ground-based platform. The system's altitude can be adjusted to maximize power production, and because the system is both functional and economical in a stationary position, it circumvents many of the controls challenges faced by kite-based wind energy systems. However, the need for generation of energy introduces pointing, efficiency, and autonomy requirements, which are not faced by conventional aerostats, thereby requiring a careful model-based control design. In this paper, we provide a dynamic model of the Altaeros system, then show how this model is leveraged in the plant design and in the design of the control system, which provides full autonomy, from takeoff, through power production, to autonomous landing. We provide simulation and experimental results that demonstrate the performance of the prototype and point to important areas where Altaeros will focus its efforts moving forward. [ABSTRACT FROM AUTHOR]

This paper presents a closed-loop flux-weakening controller for hybrid-excitation synchronous machine drives based on separate regulation of amplitude and phase angle of the armature voltage. Operating point analysis is carried out to investigate the dynamic properties of the drive and to give guidelines in the tuning of the controller. Finally, experimental tests validating the theoretical derivations are performed on a prototype hybrid-excitation drive. [ABSTRACT FROM PUBLISHER]

More electric is a platform being widely adopted by the current generation of aircraft. It offers significant benefits in terms of fuel savings and flexibility of airframe design but relies on the development of torque dense machines. This paper documents the development of an air-cooled transverse flux machine for use in short-haul aircraft to improve on-ground operational efficiency. If its potential is to be realized, this topology of the machine comes with a new set of manufacturing challenges. Two competing machine layouts with different approaches toward their fabrication are discussed. Experimental results and experiences gained from overcoming the challenges of building the machines are presented. A combined phase topology with soft magnetic composite core-back is shown to give a better rated torque, whereas a separate phase bent lamination concept gives better overload capability. [ABSTRACT FROM AUTHOR]

In this brief paper, a novel fault-tolerant control allocation scheme is proposed that has the capability to maintain closed-loop nominal performance in the case of faults/failures by effectively managing the actuator redundancy, and without reconfiguring the underlying control law. The proposed scheme relies on an a posteri approach, building on an existing state feedback controller designed using only the primary actuators. An ISM scheme is integrated with the existing controller to introduce fault tolerance. The proposed scheme uses the measured or estimated actuator effectiveness levels in order to redistribute the control signals to the healthy ones, which allows a certain class of total actuator failures to be mitigated. The effectiveness of the proposed scheme is tested in simulation using a high-fidelity nonlinear model of a large transport aircraft model. [ABSTRACT FROM AUTHOR]

This paper presents a control-based trajectory generation approach for unmanned aerial vehicles (UAVs) under dynamic constraints. It exploits the concept of optimal control to find closed-form differential equations that satisfy any arbitrary dynamic limitation mapped into kinematic constraints. Pontryagin’s Minimum Principle applies to derive a set of differential equations in which the dynamic environment is considered in the constrained Hamiltonian function. In particular, we aim to minimize the L2-norm of the control input avoiding dynamic obstacles, given initial and final boundary conditions. Lastly, this paper proposes a novel interpolation algorithm based on rational functions, referred to as rational recursive smooth trajectory (RRST) method. The method generates an analytic expression that approximates the control inputs, for which no closed-form solutions are in general attainable.

The aerospace industry is a rich source of innovation and novel technologies. However, structural drivers, such as product complexity and stringent performance requirements, inhibit the uptake of new technologies and present challenges to portfolio management specific to technology-rich environments. Although project risk is often managed through staged funding processes associated with intermediate milestones, this process is typically decoupled from portfolio valuation. In this paper, we use a simple real options binomial tree model to value the National Aeronautics and Space Administration portfolio funded through the Small Business Innovation Research program, accounting quantitatively for the funding stages and future opportunities accompanying technology infusion. For the 2009 portfolio, the average net project investment is $166k, suggesting the important role that early-stage funding plays in launching innovation efforts. We study the staged architecture to offer insight to managers of commercial and public portfolios alike. [ABSTRACT FROM AUTHOR]

In this paper, a permanent magnet alternator which presently relies on magnetic slot wedges is redesigned to give lower iron loss. The new segmented stator design is used as the basis for a validated loss study—comparing bonded lamination stacks with those held together with a punched notch. Segmentation is shown to improve the production process, reduce losses, and remove the need for wedges, while not significantly altering the acoustic performance. In the first series of prototypes, however, where notching is used to secure lamination packs, the process is shown to have adversely affected material properties of the nickel iron laminations and overall measured losses increased. In the second prototype, with thinner laminations and glued stacks, iron loss predictions and measurement agree and are less than the present slot wedge design. [ABSTRACT FROM AUTHOR]

We present in this paper a case study of the probabilistic approach to model-based diagnosis. Here, the diagnosed system is a real-world electrical power system (EPS), i.e., the Advanced Diagnostic and Prognostic Testbed (ADAPT) located at the NASA Ames Research Center. Our probabilistic approach is formally well founded and based on Bayesian networks (BNs) and arithmetic circuits (ACs). We pay special attention to meeting two of the main challenges often associated with real-world application of model-based diagnosis technologies: model development and real-time reasoning. To address the challenge of model development, we develop a systematic approach to representing EPSs as BNs, supported by an easy-to-use specification language. To address the real-time reasoning challenge, we compile BNs into ACs. AC evaluation (ACE) supports real-time diagnosis by being predictable, fast, and exact. In experiments with the ADAPT BN, which contains 503 discrete nodes and 579 edges and produces accurate results, the time taken to compute the most probable explanation using ACs has a mean of 0.2625 ms and a standard deviation of 0.2028 ms. In comparative experiments, we found that, while the variable elimination and join tree propagation algorithms also perform very well in the ADAPT setting, ACE was an order of magnitude or more faster. [ABSTRACT FROM AUTHOR]

This paper proposes and investigates an analytical method for assessing the risk of potential irreversible demagnetization in the permanent magnets (PMs) of electrical machines equipped with $n$ -stages, Halbach arrays. The higher risk of demagnetization, synonymous with Halbach arrays, imposes that the method be both load and temperature dependent. In fact, the proposed method studies the magnetic field distribution in the air gap and PM region, for various operating temperatures and expresses these fields as analytical expressions for the no-load and peak-load conditions. The model can cater for Halbach arrays with up to $n$ stages, thus making it a versatile tool that can be utilized for various Halbach configurations. Finite-element analysis is used to validate the method. The analytical tool is then used for the design and analysis of a high torque density, outer rotor, traction motor. The motor is for an aerospace application and its operating duty cycle imposes very high, short-time, peak-load conditions at elevated temperatures, posing an elevated risk of irreversible PM demagnetization. The model is used to investigate various Halbach configurations for this application, in order to reduce the demagnetization risk and also to improve the general performance of the machine. The analytical method thus provides a computationally efficient tool that can be used to predict and prevent demagnetization in Halbach-equipped electrical machines operating in harsh environments such as the aerospace sector. [ABSTRACT FROM AUTHOR]

This paper reports a propulsion motor for a solar-powered aircraft. The motor uses precompressed aluminum stator windings, with a fill factor of greater than 75%, in a permanent magnet synchronous machine. The motor performance is compared empirically to an identical machine with conventionally wound copper windings. It is shown that there are many advantages to using compressed aluminum windings in terms of weight reduction, thermal improvement, and lower cost, for the same loss and electromagnetic performance, provided a sufficiently high slot fill factor can be achieved. The design and manufacture of the compressed coils is also discussed. A modular stator arrangement is used, in the form of a solid coreback with keyed teeth to allow easy assembly of the compressed windings. It is noted that the electromagnetic performance of the machine is unaffected by the modular nature of the magnetic core. Two prototype motors, one wound with conventional copper and the other with precompressed aluminum windings, are constructed and tested. [ABSTRACT FROM PUBLISHER]

Today, many companies are facing the problem of component obsolescence in embedded systems. The incredibly fast growth rate of semiconductor companies is reducing dramatically the time components are available on the market. Twenty years ago, components remained on the market for 5 to 10 years; nowadays, they disappear from the market in less than two years. Developers of safety- or mission-critical systems are particularly sensitive to the obsolescence problem as their systems are expected to remain operative for very long periods (e.g., 30 years or more), and maintaining them fully operative is becoming difficult as the needed components may no longer be available. A possible solution for this problem may be the implementation of the needed components using FPGAs. The purpose of this paper is to provide an overview of the different possibilities designers have to face when developing such dependability-oriented solution. Also, a design flow is presented, describing its applicability to the implementation of processor cores, to be employed as a replacement of obsolete parts in safety- or mission-critical applications. Results show that there is a strong dependence of the reliability of the design with the specific application. The scrubbing process can also be optimized using the related technique. [ABSTRACT FROM AUTHOR]

Flux-switching permanent-magnet (FSPM) brushless machines have attracted considerable interest as a candidate machine technology for applications requiring high torque density and robust rotors. To date, published findings have focused exclusively on single- and three-phase FSPM machines. This paper investigates FSPM brushless machines of higher phase numbers by means of a detailed comparison of the electromagnetic performances of three-, four-, five-, and six-phase variants within the specific context of aerospace machine. Machines having both all poles and alternate poles wound are investigated, with the latter offering scope to reduce mutual coupling between phases so as to achieve improved fault tolerance. The finite-element (FE)-predicted electromagnetic performances in both machines, such as electromotive force waveform, winding inductance, cogging torque, and static torque, are validated by the experiments made on a small-scale five-phase FSPM machine. The nature of the machine specification requires that consideration must be given to mechanical stress in the rotor and the tradeoff with electromagnetic design considerations, notably the degree of rotor saliency which can be incorporated. Therefore, a mechanical FE study of the rotor mechanical stresses of multiphase FSPM machines is also comparatively assessed. [ABSTRACT FROM AUTHOR]

Links able to sustain high-speed data transfer while exposed to radiation phenomena are required by several applications, including aerospace and high-energy physics experiments. To satisfy this need, this paper outlines the design of a radiation-hard line driver for communication up to 10 Gb/s. The driver design is focused on the techniques adopted to increase its radiation hardness, namely the use of long-channel transistors, the avoidance of p-type MOSFETs and thick oxide devices. Circuital strategies to boost driver speed, such as inductive peaking, buffer chaining, and optimal layout placement and routing, are discussed and implemented to compensate for the downsides caused by adopted radiation-hard techniques. The driver, fabricated in 65 nm technology, has been experimentally tested demonstrating its ability to operate up to 10 Gb/s in a radiation-pervaded environment. In particular, after exposure to 1 Grad(SiO2) X-ray, the line driver exhibits an output signal amplitude reduction of 18.3% and a jitter increase of 5.53%. Performed temperature tests highlight that the line driver is capable to operate at 125 °C with 15.9% and 6.7% output signal swing reduction and jitter increase, respectively. The temperature tests also demonstrate the driver’s ability to work up to 160 °C with an output signal swing reduction below 25% and a jitter increase below 12%.

One of the challenging problems in sensor network systems is to estimate and track the state of a target point mass with unknown dynamics. Recent improvements in deep learning (DL) show a renewed interest in applying DL techniques to state estimation problems. However, the process noise is absent which seems to indicate that the point-mass target must be non-maneuvering, as process noise is typically as significant as the measurement noise for tracking maneuvering targets. In this paper, we propose a continuous-time (CT) model-free or model-building distributed reinforcement learning estimator (DRLE) using an integral value function in sensor networks. The DRLE algorithm is capable of learning an optimal policy from a neural value function that aims to provide the estimation of a target point mass. The proposed estimator consists of two high pass consensus filters in terms of weighted measurements and inverse-covariance matrices and a critic reinforcement learning mechanism for each node in the network. The efficiency of the proposed DRLE is shown by a simulation experiment of a network of underactuated vertical takeoff and landing aircraft with strong input coupling. The experiment highlights two advantages of DRLE: i) it does not require the dynamic model to be known, and ii) it is an order of magnitude faster than the state-dependent Riccati equation (SDRE) baseline.

Since their development in the late 1980s, lithium rechargeable batteries have enjoyed rapid growth and wide use as a commodity battery known for its higher energy density storage and lightweight convenience. These same attributes are emerging as a strong platform in power source development for the medical and aerospace sectors with highly customized applications and narrowly defined criteria. Accordingly, this new generation of lithium rechargeables must be hermetically sealed, have long-term storage capability, and zero-fault tolerances for common causes of field failures such as electrolyte leakage or short circuits from mechanical deformation. Quallion has been developing and manufacturing highly reliable lithium rechargeable cells for medical, aerospace, and specialty applications. Summarized in this paper are some key technologies developed at Quallion for designing and manufacturing of this new class of lithium rechargeable batteries. They include: 1) leakage reliability; 2) self-extinguishing electrolyte system; 3) mechanical impact resistance; 4) deep discharge storage; and 5) high reliability manufacturing. [ABSTRACT FROM PUBLISHER]

The relevance of microgravity research—i.e., research activities related to the possibility to generate and/or take advantage of an environment scantly affected by gravitational effects—is becoming more and more important for both policymakers and executives, not only in the aerospace domain but also in many other domains. However, tracing the evolution of the technological landscape deriving from microgravity research is very complex due to the fast-growing solutions emerging from such a research activity as well as their diversified nature in terms of actors and domains of relevance. This makes difficult to identify/foresee the most exploited/promising solutions related to microgravity research, set the research budget for subsequent R&D activities, recognize relevant business opportunities, and regulate access to space. Therefore, this article aims to delve into the technological outcomes of microgravity research, so revealing their main development trends (i.e., temporal trends, the geographic origins of related solutions, main technological areas, key research organizations, and the highly impacting technologies) to provide visions of the future (i.e., technology foresight) and derive implications for business and policy. To do so, we collected and analyzed a unique sample of 4401 patents, applied between 1960 and 2020, in the wide domain of microgravity research. [ABSTRACT FROM AUTHOR]

A newly developed power processing unit (PPU) offers the advantages of smaller size and lighter weight than conventional PPUs. The thrust performance of a magnetic layer type Hall thruster developed at Kyushu University with this new PPU was investigated; it showed a good performance as compared with conventional power supplies. The thrust to power ratio was improved to 58 mN/kW at discharge voltage of 150 V and anode xenon mass flow rate of 1.0 mg/s. [ABSTRACT FROM PUBLISHER]

This article deals with the impact of harmonic filters’ interactions in the aircraft grid, in particular, their influence on the control performance of each subsystem. The study has been carried out on a notional electrical system composed of two three-phase power converters—a voltage source inverter and an active front end. The beginning of the article presents the origin of the issue—trend of reducing the filter size and weight, which is especially true in the aircraft industry. Then, the roles of the filter and their design challenges are discussed. The next part of the article describes the controller’s constraints, its design, and the control system modeling approach, including a specially developed simulation tool used for the interactions analysis. Simulation results with the experimental verification are presented showing the interactions impact on the system dynamics. Finally, optimization of the filters under dynamic control constraints considering system’s components interaction are presented as the simulation tool application. [ABSTRACT FROM AUTHOR]

Some of the distinct attributes of Aerospace and Automobile Software Technologies are briefly reviewed in this article as a way of placing in collective-context the detailed technical papers that form this exciting special issue. A historical context, a unifying architectural perspective and, the rapidly changing and defining role of software is presented, especially as we look ahead to this new decade in this still young century. [ABSTRACT FROM AUTHOR]

A pulse-shaping technique superior to various other existing pulse shaping techniques has been suggested. A practical way of implementing the scheme has been discussed and the results found to be encouraging. New spike suppression (SS). Window function has also been suggested for obtaining low side lobe levels and to suppress spikes in phase shift keying spectrums that exists at high bit rate data transmission. The characteristics such as low side lobe levels and spike elimination have been achieved using new techniques that are essential for space applications [ABSTRACT FROM PUBLISHER]

This article presents a novel recursive smooth trajectory (RST) generation algorithm for application in robotics and in particular for unmanned aerial vehicles (UAVs). RST builds the trajectory recursively as a smooth polynomial path, thus a closed form trajectory satisfying any arbitrary dynamic limitation that translates into kinematic constraints (e.g., position, velocity, acceleration, etc.). Uncertainties and perturbations in the constraints are also discussed, modeled, and finally included in the calculation of the polynomial trajectory coefficients. Moreover, due to its recursive formulation, RST enables an immediate extension toward the solution of a trajectory optimization problem. In particular, it is shown that the minimum-snap piecewise polynomial trajectory can be interpreted as a special case of RST. The effectiveness of the proposed algorithm is demonstrated numerically via two illustrative scenarios. Its application to a UAV structure is also discussed to highlight the advantage of a smooth path over a piecewise one. Finally, the computational complexity and memory requirements are analyzed. [ABSTRACT FROM AUTHOR]

This article investigates the design of a 250 kW permanent magnet (PM) machine used for aircraft propulsion. The focus is to pursue high specific power (>20 kW/kg), high efficiency (>95%), and low thermal resistance direct-cooling design for the demanding aerospace applications. The proposed key-enabling technology is additively manufactured hollow conductors integrated with heat pipes. Compared to the existing high specific power PM machines for aerospace applications, the proposed design features a much lower speed – 5000 r/min without any torque amplifier, which helps promote the specific power of the overall system. Based on parametric finite-element analysis, tradeoff studies on a variety of winding configurations as well as geometrical parameters have been carried out, highlighting their impact on specific power, winding ac losses, and efficiency. AlSi10Mg coil samples printed by direct metal laser sintering as well as thermal management system have been demonstrated to show the feasibility of the concepts. [ABSTRACT FROM AUTHOR]

There has been considerable activity in recent years in developing analytical techniques for hard real-time systems. Inevitably these techniques make simplifying assumptions so as to reduce the complexity of the problem to be solved. Unfortunately this leads to a gap between theory and engineering practice. This paper presents new analysis that enables the costs of the scheduler (clock overheads, queue manipulations and release delays) to be factored into the standard equations for calculating worst-case response times. As well as predicting the true behavior of realistic systems, the analysis also allows free parameters, such as clock interrupt rate, to be determined. [ABSTRACT FROM AUTHOR]

Modern electrical machines employed in transportation applications are required to provide high performance in terms of power (and torque) density. At the same time, being these applications safety-critical, a significant level of reliability and/or fault tolerance is expected. Among all the factors which can compromise motors reliability, partial discharges (PDs) inception is one of the most crucial, in particular for low voltage, random wound machines. This article presents an extensive experimental investigation on PDs in electrical machines for aerospace applications. Measurements are carried out using both sinusoidal and fast-rising pulses in a representative aerospace environment, emulating the typical ambient conditions encountered throughout a commercial aircraft mission, and beyond (i.e., down to 30 mbar). As a main result of the investigation, it is proved that electrical machines employed for actuating primary flight control surfaces feature a higher risk of PDs inception. Therefore, their insulation system demands an extremely careful design. [ABSTRACT FROM AUTHOR]

Integrated health monitoring is beneficial, but due to reliability, weight, size, wiring, and other constraints, the incorporation of instrumentation onto aircraft propulsion systems is limited. Conventional wired sensing systems are not always feasible due to the size, weight constraints, and issues associated with cable routing. This article presents an integrated and self-powered wireless system for high-temperature (above 125 °C) environments powered by a thermoelectric generator (TEG) for bearing condition monitoring. A TEG with an internal oil-cooling chamber is proposed to achieve higher-energy output for small temperature gradient recorded in the jet engine in comparison with other TEGs with heat sinks. The experimental results demonstrate that, under a simulated engine environment, the TEG can provide sufficient energy for a wireless sensing system to collect environmental data every 46 s and transmit every 260 s during the critical takeoff phase of the flight and part of cruise. [ABSTRACT FROM AUTHOR]

Soft error protection is a paramount requirement for memories exposed to radiation environment. To satisfy the demand, a radiation-hardened new-quatro 10T memory cell is proposed in this brief, which is immune to single-node upset and also has high resilience to multinode upset while features read-disturbance-free benefiting from its internal quad-node interlocked feedback mechanism. Simulation results show that it provides ample radiation robustness to single event and gives $1.75\times $ improvements in multinode upset tolerance when compared with the previous 12T dual-interlocked storage cell (DICE-12T) bitcell, signifying the higher fault tolerance capability. In addition, the proposed design also achieves $6.48\times $ enhancement in read noise margin when compared with the DICE-12T bitcell while compromising only $2.1\times $ larger area than a reference 6T cell based on a 65-nm logic design rule, exhibiting the superiority in read stability. [ABSTRACT FROM AUTHOR]

As mentioned in a recent editorial in this magazine [1], distributed generation (renewables), automotive and, in general, transport and industrial utilization are fast changing the structure of electrical assets as well as the typologies and design of electrical apparatus. This is due mostly to the more widespread use of renewable generation and the electrification of transport, including power electronic converters and inverters, which can provide higher voltage, lower losses and make the asset more efficient and power dense. In the long run, medium voltage (MV) transformers will tend to disappear and perhaps high voltage (HV) transformers may be endangered. The future typical industrial, transport and, likely, T&D assets will be made by hybrid networks where power will be delivered in AC or DC, depending on convenience, and most of the loads (rotating machines) will be controlled by power electronics. [ABSTRACT FROM AUTHOR]