Eindhoven University of Technology

Ising machines are attractive for efficiently solving NP‐hard combinatorial optimization problems (COPs). In this work, a scalable monolithic‐3D (M3D) oscillatory Ising machine (OIM) is proposed using ferroelectric field‐effect transistors (FeFETs) serving as an in‐memory routing switch (RS) and bi‐stable resistor (biristor)‐based oscillators for the first time. The M3D OIM achieves low static power consumption while offering high reconfigurability. Through careful control of FeFET routing switches, weights of the Ising model are embedded in coupled biristors. The performance is validated through simulations and experiments, in successfully solving King's graph sub‐problems and the MaxCUT problem. By leveraging the intrinsic OIM features of parallel computing together with M3D integration, it is reported that the M3D OIM outperforms reported OIMs in scalability and speed. Such an approach provides new insights and significant potential for solving COPs.

Four-dimensional (4D) constellations are optimized using geometric shaping (GS) with orthant symmetry (OS) over realistic optical channel models targeting next-generation single-span systems. The optical fiber is modeled via the Manakov equation and is implemented using the split-step Fourier method (SSFM) in a Monte-Carlo based approach. Additional noise sources and losses are added making the link model relevant in practice. Constellations are optimized for different cardinalities, forward error correction code rates, and symbol rates. The SSFM-optimized constellations are reported to offer up to 4% in reach increase with respect to conventional quadrature amplitude modulation (QAM). Comparisons against existing additive white Gaussian noise (AWGN)-optimized constellations show that SSFM-optimized constellations with OS generally negligibly outperform AWGN-optimized counterparts. This somewhat unexpected result leads to the conclusion that AWGN-optimized constellations are a good choice for realistic single-span optical links.

Dynamic contrast-enhanced ultrasound (DCEUS) is an imaging modality for assessing microvascular perfusion and dispersion kinetics. However, the presence of speckle noise may hamper the quantitative analysis of the contrast kinetics. Common speckle denoising techniques based on low-rank approximations typically model the speckle noise as white Gaussian noise (WGN) after the log transformation and apply matrix-based algorithms. We address the high dimensionality of the 4D DCEUS data and apply low-rank tensor decomposition techniques to denoise speckles. Although there are many tensor decompositions that can describe low rankness, we limit our research to multilinear rank and tubal rank. We introduce a gradient-based extension of the multilinear singular value decomposition to model low multilinear rankness, assuming that the log-transformed speckle noise follows a Fisher-tippet distribution. In addition, we apply an algorithm based on tensor singular value decomposition to model low tubal rankness, assuming that the log-transformed speckle noise is WGN with sparse outliers. The effectiveness of the methods is evaluated through simulations and phantom studies. Additionally, the tensor-based algorithms’ real-world performance is assessed using DCEUS prostate recordings. Comparative analyses with existing DCEUS denoising literature are conducted, and the algorithms’ capabilities are showcased in the context of prostate cancer classification. The addition of Fisher-tippet distribution did not improve the results of tr-MLSVD in the in vivo case. However, most cancer markers are better distinguishable when using a tensor denoising technique than state-of-the-art approaches.

Molecular machine learning models often fail to generalize beyond the chemical space of their training data, limiting their ability to reliably perform predictions on structurally novel bioactive molecules. To advance the ability of machine learning to go beyond the ‘edge’ of their training chemical space, we introduce a joint modeling approach that combines molecular property prediction with molecular reconstruction, enabling us to estimate model generalizability through a new reconstruction-based ‘unfamiliarity’ metric. Via a systematic analysis spanning more than 30 bioactivity datasets, we demonstrate that unfamiliarity not only effectively identifies out-of-distribution molecules but also serves as a reliable predictor of classifier performance. Even when faced with the presence of strong distribution shifts, unfamiliarity yields robust and meaningful molecular insights that go unnoticed by traditional methods. Our findings highlight that joint modelling can be a powerful strategy for extending the reach of machine learning models into uncharted regions of chemical space, advancing the discovery of diverse and novel molecules.

The electric field is the driving force behind every plasma. Electric field induced second harmonic generation (E-FISH) is a diagnostic able to obtain the electric field with high temporal and spatial resolution, is considered non-invasive and can be applied to almost any type of plasma with high sensitivity. However, the high fluence laser beam used as a probe in this technique, can interact with the gas and induce charges, which can subsequently influence the plasma. In this work, E-FISH is applied on non-thermal pulsed plasma jets in N2 flowing into atmospheric air. In these jets, ionization fronts propagate along the axis of the jet, which are highly reproducible and periodic. This allows for phase resolved measurements. A nanosecond and a picosecond pulsed laser, both operating at 1064 nm, are used as sources. For the first time, the obtained E-FISH signals measured with both lasers are compared to each other. The results deviate significantly between the two lasers, which can be explained by laser induced guiding of the streamers. This is observed by taking ICCD images of the plasma trajectory. At the position where the plasma crosses the laser beam path, the plasma branches. This reveals that E-FISH is also invasive under some conditions. The profiles obtained with the picosecond laser are in good qualitative agreement with previous coherent Raman scattering-based four-wave mixing results on the same plasma source and therefore the picosecond laser is considered non-invasive. In future E-FISH measurements, the influence of the laser beam on the E-FISH signal should be taken into account to prevent changing the plasma behavior. By decreasing the laser power or using a shorter laser pulse, successful measurements can be performed.

We present a model for the particle balance in the post-disruption runaway electron plateau phase of a tokamak discharge. The model is constructed with the help of, and applied to, experimental data from TCV discharges investigating the so-called ‘low-Z benign termination’ runaway electron mitigation scheme. In the benign termination scheme, the free electron density is first reduced in order for a subsequently induced MHD instability to grow rapidly and spread the runaway electrons widely across the wall. We show that the observed non-monotonic dependence of the free electron density with the measured neutral pressure is due to plasma re-ionization induced by runaway electron impact ionization. At higher neutral pressures, more target particles are present in the plasma for runaway electrons to collide with and ionize. Parameter scans are conducted to clarify the role of the runaway electron density and energy on the free electron density, and it is found that only the runaway electron density has a noticeable impact. While the free electron density is shown to be related to the spread of heat fluxes at termination, the exact cause for the upper neutral pressure limit remains undetermined and an object for further study.

This paper surveys interactions between choices of elliptic curves and the security of elliptic-curve cryptography. Attacks considered include not just discrete-logarithm computations but also attacks exploiting common implementation pitfalls.

Capillary porous structure (CPS) based liquid metal divertors are currently being investigated as a possible alternative to the tungsten based solid plasma facing components (PFCs). The ability of CPS based technologies to withstand high heat fluxes (> 20 MW/m²) has been already demonstrated in linear devices as well as tokamaks. One of the key aspects of a liquid metal divertor is the erosion of the liquid metal with the subsequent contamination of the plasma. The liquid can be eroded by physical sputtering, evaporation and thermally enhanced sputtering. The absence of a theoretical model or detailed empirical data of Sn thermally enhanced sputtering prohibits reliable predictions of Sn erosion by fusion plasma. Especially in high density tokamak plasmas, thermally enhanced sputtering appears to be the dominant contributor to total erosion. To empirically evaluate the thermally enhanced sputtering yields an experimental campaign was conducted at the Nano-PSI device (Te = 0.3–0.8 eV, $\Gamma_{i} = 5 \times 10^{18} {\text{ m}}^{ - 2} \;{\text{s}}^{ - 1}$) with Sn surfaces exposed to homogeneous plasma of various ion species (Ar, Ne, H, He). The effect of ion impact energy on the sputtering yields was studied as well by biasing of the the liquid surface in range of − 10 to − 80 V. In case of Ar, Ne and He the Sn was exposed as a free-flowing surface and for H it was exposed in a stainless-steel capillary porous structure (CPS) to negate the observed H spitting of the free liquid surface. This work presents the measured thermally enhanced sputtering yields, with focus on the observed phenomena, such as plasma species and impact energy dependency.

Current organic light-emitting diode (OLED) technology uses light-emitting molecules in a molecular host. We report green circularly polarized luminescence (CPL) in a chirally ordered supramolecular assembly, with 24% dissymmetry in a triazatruxene (TAT) system. We found that TAT assembled into helices with a pitch of six molecules, associating angular momentum to the valence and conduction bands and obtaining the observed CPL. Cosublimation of TAT as the “guest” in a structurally mismatched “host” enabled fabrication of thin films in which chiral crystallization was achieved in situ by thermally triggered nanophase segregation of dopant and host while preserving film integrity. The OLEDs showed external quantum efficiencies of up to 16% and electroluminescence dissymmetries ≥10%. Vacuum deposition of chiral superstructures opens new opportunities to explore chiral-driven optical and transport phenomena.

In software-engineering research, many empirical studies are conducted with open-source or industry developers. However, in contrast to other research communities like economics or psychology, only few experiments use financial incentives ( i.e ., paying money) as a strategy to motivate participants’ behavior and reward their performance. The most recent version of the SIGSOFT Empirical Standards mentions payouts only for increasing participation in surveys, but not for mimicking real-world motivations and behavior in experiments. Within this article, we report a controlled experiment in which we tackled this gap by studying how different financial incentivization schemes impact developers. For this purpose, we first conducted a survey on financial incentives used in the real-world, based on which we designed three incentivization schemes: (1) a performance-dependent scheme that employees prefer, (2) a scheme that is performance-independent, and (3) a scheme that mimics open-source development. Then, using a between-subject experimental design, we explored how these three schemes impact participants’ performance. Our findings indicate that the different schemes can impact participants’ performance in software-engineering experiments. Our results are not statistically significant, possibly due to small sample sizes and the consequent lack of statistical power, but with some notable trends that may inspire future hypothesis generation. Our contributions help understand the impact of financial incentives on participants in experiments as well as real-world scenarios, guiding researchers in designing experiments and organizations in compensating developers.

Neuromodulation with low‐intensity focused ultrasound (LIFUS) holds significant promise for noninvasive treatment of neurological disorders, but its success relies heavily on accurately targeting specific brain regions. Computational model predictions can be used to optimize LIFUS, but uncertain acoustic tissue properties can affect prediction accuracy. The Monte Carlo method is often used to quantify the impact of uncertainties, but many iterations are generally needed for accurate estimates. We studied a surrogate model based on polynomial chaos expansion (PCE) to quantify the uncertainty in the LIFUS acoustic intensity field caused by tissue acoustic property uncertainties. The PCE approach was benchmarked against Monte Carlo method for LIFUS in three different head models. We also investigated the effect of the number of PCE samples on the accuracy of the surrogate model. Our results show that the PCE surrogate model requires only 20 simulation samples to estimate the mean and standard deviation of the acoustic intensity field with high accuracy compared to 100 samples needed for Monte Carlo method. The root mean squared percentage error (RMSPE) in the mean acoustic intensity field was less than 1.5%, with a maximum error of less than 0.5 W/cm ² (< 1% of the focus peak intensity in water), while the RMSPE in the standard deviation was less than 9%, with a maximum error of less than 0.3 W/cm ² . The accuracy of the PCE surrogate model, and the limited number of iterations it requires makes it a promising tool for quantifying the uncertainty in the acoustic intensity field in LIFUS applications.

This manuscript focuses on mitigating the effect of deception attacks on control signals, that is, in the presence of an adversary that tampers with data coming from the controller to the system actuators in order to degrade the plant performance. We propose adding Multiple‐Inputs Multiple‐Outputs (MIMO) filters to the loop, between the received control actions (which are potentially corrupted by attacks) and the plant actuators. These filters are designed to dynamically steer the reachable set induced by the attack signals to a known safe region of the state space. We provide a synthesis framework (built in terms of the solution of a collection of semidefinite programs) to design the filters so that attack‐free control signals are distorted as little as possible–in terms of and norms of the difference between original and filtered control signals–and the trajectories are guaranteed to be contained in a predefined safe set. The results are illustrated through a simulation case focusing on the stability augmentation system of an airplane.

Polymersomes with surface-integrated nanoparticles, in which a smaller sphere is attached to a larger capsule, are typically formed through complex processes like membrane deformation, polymerization, or membrane functionalization. This complexity restricts facile application of this unusual topology, for example in drug delivery or nanomotor science. Our study introduces a robust method for crafting polymersomes with surface-integrated nanoparticles using a hierarchical phase separation approach. By co-assembling block copolymers with aromatic aggregation-induced emission (AIE) moieties as side chains and photothermal-responsive guest molecules (PTM), spontaneous sequential phase separation processes occur that lead to their controlled formation. Polymer-rich liquid droplets form first, followed by internal phase separation of the guest molecules, which determines the formation of asymmetric morphology. This mechanism is elucidated in detail using liquid-phase transmission and cryogenic transmission electron microscopy (LP-TEM and cryo-TEM) and corroborated by theoretical simulations of the interaction forces between the block copolymers and guest molecules. Finally, the application potential of polymersomes with surface-integrated nanoparticles as nanomotors is demonstrated.