Full Verification Research Articles

CFD simulation and water model experiments with overflow-type supergravity reactor set up for continuously removing inclusions from aluminum melt

In this work, an overflow-type supergravity reactor has been tested for removal of inclusions from aluminum melt. A combination of numerical and physical simulations was employed to investigate the continuous separation process of recycled aluminum melt and inclusions, with a focus on evaluating the effects of reactor structures, process parameters, and inclusion characteristics on the inclusion separation efficiency. The results of numerical simulation indicate that the inclusion separation efficiency is positively related to overflow pipe length (L), overflow pipe installation height (H), gravity coefficient (G), inclusion density (ρ) and inclusion diameter (d), and negatively related to overflow pipe diameter (Φ) and melt inflow rate (Q). The overflow-type supergravity reactor exhibited excellent performance in separating inclusions from recycled aluminum melt. Under the conditions of L = 40 mm, H = 108 mm, Φ = 10 mm, G = 500, and Q = 0.5 kg/s, the separation efficiency of 18 μm Al2O3 inclusions reached nearly 100 %. The high consistency between the results of numerical and physical simulations provided full verification of the reliability and accuracy of the numerical simulation.

Observation of the nonanalytic behavior of optical phonons in monolayer hexagonal boron nitride

Phonon splitting of the longitudinal and transverse optical modes (LO-TO splitting), a ubiquitous phenomenon in three-dimensional polar materials, will break down in two-dimensional (2D) polar systems. Theoretical predictions propose that the LO phonon in 2D polar monolayers becomes degenerate with the TO phonon, displaying a distinctive “V-shaped” nonanalytic behavior near the center of the Brillouin zone. However, the full experimental verification of these nonanalytic behaviors has been lacking. Here, using monolayer hexagonal boron nitride (h-BN) as a prototypical example, we report the comprehensive and direct experimental verification of the nonanalytic behavior of LO phonons by inelastic electron scattering spectroscopy. Interestingly, the slope of the LO phonon in our measurements is lower than the theoretically predicted value for a freestanding monolayer due to the screening of the Cu foil substrate. This enables the phonon polaritons in monolayer h-BN/Cu foil to exhibit ultra-slow group velocity (~5 × 10−6c, c is the speed of light) and ultra-high confinement (~ 4000 times smaller wavelength than that of light). These exotic behaviors of the optical phonons in h-BN presents promising prospects for future optoelectronic applications.

PLMP - Point-Line Minimal Problems in Complete Multi-View Visibility.

We present a complete classification of all minimal problems for generic arrangements of points and lines completely observed by calibrated perspective cameras. We show that there are only 30 minimal problems in total, no problems exist for more than 6 cameras, for more than 5 points, and for more than 6 lines. We present a sequence of tests for detecting minimality starting with counting degrees of freedom and ending with full symbolic and numeric verification of representative examples. For all minimal problems discovered, we present their algebraic degrees, i.e.the number of solutions, which measure their intrinsic difficulty. It shows how exactly the difficulty of problems grows with the number of views. Importantly, several new minimal problems have small degrees that might be practical in image matching and 3D reconstruction.

Steady melting in material extrusion additive manufacturing

PurposeA main cause of defects within material extrusion (MatEx) additive manufacturing is the nonisothermal condition in the hot end, which causes inconsistent extrusion and polymer welding. This paper aims to validate a custom hot end design intended to heat the thermoplastic to form a melt prior to the nozzle and to reduce variability in melt temperature. A full 3D temperature verification methodology for hot ends is also presented.Design/methodology/approachInfrared (IR) thermography of steady-state extrusion for varying volumetric flow rates, hot end temperature setpoints and nozzle orifice diameters provides data for model validation. A finite-element model is used to predict the temperature of the extrudate. Model tuning demonstrates the effects of different model assumptions on the simulated melt temperature.FindingsThe experimental results show that the measured temperature and variance are functions of volumetric flow rate, temperature setpoint and the nozzle orifice diameter. Convection to the surrounding air is a primary heat transfer mechanism. The custom hot end brings the melt to its setpoint temperature prior to entering the nozzle.Originality/valueThis work provides a full set of steady-state IR thermography data for various parameter settings. It also provides insight into the performance of a custom hot end designed to improve the robustness of melting in MatEx. Finally, it proposes a strategy for modeling such systems that incorporates the metal components and the air around the system.

Gænice: A general model for magnon band structure of artificial spin ices

Arrays of artificial spin ices exhibit reconfigurable ferromagnetic resonance modes that can be leveraged and designed for potential applications. However, analytical and numerical studies of the frequency response of artificial spin ices have been restricted in scope due to the need of take into account nonlocal dipole fields in theoretical calculations or by long computation times in micromagnetic simulations. Here, we introduce Gænice, a framework to compute magnon dispersion relations of arbitrary artificial spin ice configurations. Gænice makes use of a tight-binding approach to compute the magnon bands. It also provides the user control over the interaction terms included, e.g., external field, shape anisotropy, exchange, and dipole, making Gænice useful for computing ferromagnetic resonances for a variety of structures, such as multilayers and ensembles of weakly or non-interacting nanoparticles. Because it relies on a semi-analytical model, Gænice is computationally inexpensive and efficient. This makes it an attractive tool for the exploration of large parameter spaces. We expect Gænice to help guide the development of novel artificial spin ices geometries and specific micromagnetic simulations for full quantitative verification.

Development of a Graph-Based Collision Risk Situation Model for Validation of Autonomous Ships’ Collision Avoidance Systems

In the maritime industry, the systematic validation of collision avoidance systems of autonomous ships is becoming an increasingly important issue with the development of autonomous ships. The development of collision avoidance systems for autonomous ships faces inherent risks of programming errors and has mostly been tested in limited scenarios. Despite efforts to verify these systems through scenario testing, these scenarios do not fully represent the complex nature of real-world navigation, limiting full system verification and reliability. Therefore, this study proposed a method for analyzing collision risk situations extracted from AIS data through graph-based modeling and establishing validation scenarios. This methodology categorizes collision risk scenarios according to their centrality and frequency and demonstrates how simple collision risk situations gradually evolve into harsh situations.

Procedural Obstacles in Cases of Appealing Decisions, Actions, Inaction of the National Agency for on Corruption Prevention

The relevance of the article lies in the fact that fair and correct resolution of administrative cases involving appeals against decisions, actions and omissions of the National Agency for the Prevention of Corruption is possible only if all the principles of administrative justice are observed. Good faith in the exercise of procedural rights and strict observance of obligations by all participants to administrative proceedings is defined as one of the principles of administrative justice, and its observance plays a key role in achieving the objective of administrative justice. The purpose of the article is to analyze procedural obstacles, in particular, abuse of procedural rights, in the course of consideration of cases involving appeals against decisions, actions and inactions of the National Agency for the Prevention of Corruption. The study applies dialectical, formal legal, comparative legal, logical and semantic, statistical methods of scientific knowledge, as well as methods of observation, forecasting, classification and grouping, and prediction. The author examines certain aspects of the organization and activities of the National Agency for the Prevention of Corruption. It is proved that the most common administrative cases involving appeals against decisions, actions or omissions of the NAPC are the recognition as unlawful and the reversal of the decision of this public administration entity on the results of a full verification of the declaration of a person authorized to perform the functions of the State or local self-government. It is emphasized that procedural obstacles may arise during consideration of cases involving appeals against decisions, actions, and inactions of a public authority. The author examines such a procedural obstacle as abuse of procedural rights. The author analyzes the dual aspect of abuse of procedural rights, in particular, the substantive and procedural aspects. The author establishes that abuse of procedural rights which have a substantive legal aspect may arise when applying to an administrative court. It is noted that the procedural and legal aspect is related to the abuse of procedural rights at various procedural stages of administrative proceedings to appeal against decisions, actions and inactions of the NAPC, in particular: 1) opening of proceedings; 2) preparatory proceedings; 3) consideration of the case on the merits; 4) adoption and adoption of a court decision. The author provides the stages at which abuse of procedural rights may occur, given that the case is considered in the form of general action proceedings by the court of first instance. Based on the study, the author formulates conclusions and provides recommendations that abuse of procedural rights as a procedural obstacle in administrative cases concerning appeals against decisions, actions, and inactions of the NAPC may have a dual purpose: to create procedural obstacles and to delay the consideration of a case. The application of procedural consequences by the court depends on the type of abuse of procedural rights committed at a particular stage of the proceedings.

Efficient Layered Parallel Architecture and Application for Large Matrix LDPC Decoder

For a 50G passive optical network (PON) low-density parity-check (LDPC) decoder, decoding performance and area efficiency must be balanced. This paper adopts a layered decoder method to improve the area efficiency of the decoder. By parallel processing of three submatrices and storage reuse of node information, optimizing the matrix partitioning and processing order of the 50G-PON standard, the throughput of 1235 bps was reached under 100 MHz circuit frequency in field-programmable gate array (FPGA) implementation, and 9.864 Gbps was achieved based on Taiwan semiconductor manufacturing company (TSMC) 65 nm synthesis with 800 MHz circuit frequency in an area of 2.61 mm2 by proposing a mechanism of spare decision storage to avoid errors caused by quantization overflow of the decoder and using full verification to terminate decoding in advance to improve performance. Finally, at an input bit error rate (BER) of 2.3×10−2 (signal-to-noise ratio (SNR) of about 3.72 dB), the output BER was lower than 10−12, and the throughput area rate (TAR) also increased by 2 to 4 times compared with other papers. In conclusion, an area-efficient LDPC decoder without sacrificing decoding performance is made.

The fast multipole method–accelerated line integration boundary element method for 3D heat conduction analysis with heat source

Purpose3D steady heat conduction analysis considering heat source is conducted on the fundamental of the fast multipole method (FMM)-accelerated line integration boundary element method (LIBEM).Design/methodology/approachDue to considering the heat source, domain integral is generated in the traditional heat conduction boundary integral equation (BIE), which will counteract the well-known merit of the BEM, namely, boundary-only discretization. To avoid volume discretization, the enhanced BEM, the LIBEM with dimension reduction property is introduced to transfer the domain integral into line integrals. Besides, owing to the unsatisfactory performance of the LIBEM when it comes to large-scale structures requiring massive computation, the FMM-accelerated LIBEM (FM-LIBEM) is proposed to improve the computation efficiency further.FindingsAssuming N and M are the numbers of nodes and integral lines, respectively, the FM-LIBEM can reduce the time complexity from O(NM) to about O(N+ M), and a full discussion and verification of the advantage are done based on numerical examples under heat conduction.Originality/value(1) The LIBEM is applied to 3D heat conduction analysis with heat source. (2) The domain integrals can be transformed into boundary integrals with straight line integrals by the LIM. (3) A FM-LIBEM is proposed and can reduce the time complexity from O(NM) to O(N+ M). (4) The FM-LIBEM with high computational efficiency is exerted to solve 3D heat conduction analysis with heat source in massive computation successfully.

SoC Protocol Implementation Verification Using Instruction-Level Abstraction (ILA) Specifications

In modern systems-on-chips (SoCs) several hardware protocols are used for communication and interaction among different modules. These protocols are complex and need to be implemented correctly for correct operation of the SoC. Therefore, protocol verification has received significant attention. However, this verification is often limited to checking high-level properties on a protocol specification or an implementation. Verifying these properties directly on an implementation faces scalability challenges due to its size and design complexity. Further, even after some high-level properties are verified, there is no guarantee that an implementation fully complies with a given specification, even if the same properties have also been checked on the specification. We address these challenges and gaps by adding a layer of component specifications, one for each component in the protocol implementation, and specifying and verifying the interactions at the interfaces between each pair of communicating components. We use the recently proposed formal model termed the Instruction-Level-Abstraction (ILA) as a component specification, which includes an interface specification for the interactions in composing different components. The use of ILA models as component specifications allows us to decompose the complete verification task into two sub-tasks – checking that the composition of ILAs is sequentially equivalent to a verified formal protocol specification, and checking that the protocol implementation is a refinement of the ILA composition. This check requires that each component implementation is a refinement of its ILA specification, and includes interface checks guaranteeing that components interact with each other as specified. We have applied the proposed ILA-based methodology for protocol verification to several third-party design case studies. These include an AXI on-chip communication protocol, an off-chip communication protocol, and a cache coherence protocol. For each system, we successfully detected bugs in the implementation, and show that the full formal verification can be completed in reasonable time and effort.

Electric field in APTD in nitrogen determined by EFISH, FNS/SPS ratio, α-fitting and electrical equivalent circuit model

We investigate the electric field development in weak microseconds-lasting atmospheric pressure Townsend discharge operated in a barrier discharge arrangement in pure nitrogen. The electric field is determined using four different methods: laser-aided electric field induced second harmonics (EFISH), optical emission-based first negative/second positive systems (FNS/SPSs of molecular nitrogen) intensity ratio, electrical equivalent circuit approach and via determination of the Townsend first coefficient from the spatial optical emission profile. The resulting values of the electric field obtained by these respective methods, regardless of the differences in absolute values, lie within a reasonable range. The limitations and advantages of all methods are discussed in detail for the investigated discharge. The EFISH measurements are supported by re-computation of the effective interaction-path of the laser using an electrostatic model. The FNS/SPS method provides systematically higher values compared to other methods. We discuss in detail the potential origin of this discrepancy, as this method is at the limit of its applicability due to the low E/N values and we also consider the impossibility of full verification of the underlying assumptions. The focused discussion addresses best-practice issues and identifies possible future steps to improve each of the four methods under given conditions.

A Fast Method to Estimate Through-Bump Current for Power Delivery Verification

Due to the mismatch between the package scaling and the relentless silicon technology scaling, the limited power supply bumps have to bear more stresses on bump reliability. A too high through-bump current may induce increased thermal and mechanical issues, thereby damaging the integrity of solder joint micro-structure. Thus, it is critical to analyze the through-bump current under different test scenarios at sign off to ensure bump integrity. Since the full chip power delivery verification needs to solve a linear system with billions of nodes, it is then very time-and resource-consuming to repeatedly conduct such bump integrity check during ECO. In this paper, we present a fast through-bump current estimation methodology for power delivery verification, which can significantly reduce the computational complexity while maintaining accuracy. Experimental results demonstrate that the proposed methodology can achieve very high accuracy with a relative error of around 0.6% and a maximum error of around 1.5% across 4 different designs with 1-2 orders of magnitude speed-up.

Guarding Against Catastrophic Biological Risks: Preventing State Biological Weapon Development and Use by Shaping Intentions.

Guarding Against Catastrophic Biological Risks: Preventing State Biological Weapon Development and Use by Shaping Intentions.

Photonic generation of dual-band dual-chirp waveforms with anti-dispersion transmission.

A photonic approach for generating dual-band dual-chirp waveforms with the capability of anti-dispersion transmission is proposed. In this approach, an integrated dual-drive dual-parallel Mach-Zehnder modulator (DD-DPMZM) is adopted to realize single-sideband modulation of a RF input and double-sideband modulation of baseband signal-chirped RF signals. By properly presetting the central frequencies of the RF input and the bias voltages of DD-DPMZM, dual-band dual-chirp waveforms with anti-dispersion transmission can be achieved after photoelectronic conversion. A complete theoretical analysis of the operation principle is presented. Full experimental verification of the generation and anti-dispersion transmission of dual-chirp waveforms centered at 2.5 and 7.5GHz as well as 2 and 6GHz over two dispersion compensating modules with dispersion values equivalent to 120km or 100km standard single-mode fiber is successfully carried out. The proposed system features a simple architecture, excellent reconfigurability, and immunity to dispersion-induced power fading, which are highly desired in distributed multi-band radar networks with optical-fiber-based transmission.

Benchtop nuclear magnetic resonance performance evaluation according to ASTM E691-22 on a population of instruments: Molar substitution determination in hydroxypropyl betadex as a case study for use in quality control environments.

The inclusion of quantitative nuclear magnetic resonance (qNMR) spectroscopy in industry has historically been stifled by a lack of accessibility, caused in-part by the large costs of traditional high-field spectrometers, the maintenance required for these, and the expertise necessary to manage and use them. In recent years, the emergence of benchtop NMR technology, an accessible, affordable, and automatable alternative, has led to a more feasible incorporation of NMR into quality control spaces, an area traditionally reserved for other techniques such as gas chromatography and liquid chromatography, which are routinely combined with detection techniques such as mass spectrometry. While these techniques are commonly used in analyzer-type applications using gold standard methods of analysis, wherein an instrument is dedicated to performing specific assays, this remains uncommon for NMR. Herein, we perform a full method verification using benchtop qNMR on a population of benchtop NMR instruments according to the ASTM designation E691-22, a standard used to determine the precision of a test method. To our knowledge, this is the first published example of this type of study for benchtop NMR spectroscopy. For this work, a total of five analysts performed assays on 23 different benchtop NMR instruments for the analysis of hydroxypropyl betadex according to the USP-NF method, and the results are compared using a variety of statistical methods. The results of this work demonstrate that benchtop NMR technology is effective and robust under repeatability and reproducibility conditions and is a powerful tool for these types of routine quality control analyses.

3D Electrochemical-Mechanical Battery Simulation Tool: Implementation with Full Cell Simulations and Verification with Operando X-ray Tomography

Most commercially used electrode materials contract and expand upon cycling. This change in volume influences the microstructure of the cell stack, which in turn impacts a range of performance parameters. Since direct observation of these microstructural changes with operando experiments is challenging and time intensive, a simulation tool that takes a real or artificially generated 3D microstructure and captures the volumetric changes in a cell during cycling would be valuable to enable rapid understanding of the impact of material choice, electrode and cell design, and operating conditions on the microstructural changes and identification of sources of mechanically-driven cell aging. Here, we report the development and verification of such a 3D electrochemical-mechanical tool, and provide an example use-case. We validate the tool by simulating the microstructural evolution of a graphite anode and a Li(Ni,Mn,Co)O2 cathode during cycling and comparing the results to X-ray tomography datasets of these electrodes taken during cycling. As an example use case for such a simulation tool, we explore how different volumetric expansion behaviors of the cathode material impact strain in the cell stack, illustrating how the material selection and its operation impact the mechanical behavior inside a cell.

Checking Just Pairs of Threads for Efficient and Scalable Incremental Verification of Multithreaded Programs

Many techniques of automated verification target multithreaded programs, because subtle interactions between threads may trigger concurrency errors such as deadlocks and data races. However, techniques and tools involving systematic exploration of the whole space of possible thread interleavings do not scale to large software systems, despite various clever algorithmic optimizations. A viable approach is to use incremental verification techniques that, in each run, focus just on the recently modified code and the relatively small number of affected execution traces, and therefore can provide results (bug reports) very quickly. In this paper we present a new algorithm for incremental verification of multithreaded programs based on the pairwise approach, whose key idea is systematic exploration of all possible thread interleavings just for specific relevant pairs of threads. We implemented the algorithm with Java Pathfinder as the backend verification tool, and evaluated it on several multithreaded Java programs. Results show that our incremental algorithm (1) can find errors very fast, (2) greatly reduces time needed for complete safety verification, and (3) it can find the same errors as full verification of the whole state space.

Advanced GNC-oriented modeling and simulation of Vertical Landing vehicles with fuel slosh dynamics

This paper introduces a flexible framework to enable high-fidelity simulations of the fuel slosh dynamics for verification of the Guidance, Navigation and Control (GNC) algorithms. The sloshing phenomenon must be tackled during the control system design phase and the GNC software run and validated within appropriate simulation frameworks. Equivalent mechanical models can well approximate sloshing under specific assumptions, allowing the derivation of the multibody vehicle’s equations of motion; however, while suitable for analysis and control synthesis purposes, this approach presents several limitations for implementation as a simulation model. In this work, the multibody plant embedding slosh dynamics is modeled by means of the DLR’s Vertical Landing Vehicles Library (VLVLib) written using the object-oriented Modelica modeling language. The advantages of using Modelica are explored throughout the paper. Given that control synthesis, analyses and simulation campaigns are usually performed in the Matlab/Simulink environment, a core point of the proposed solution is to achieve a good synergy within the latter and the Modelica plant model with the least readaptation burden for the developer. The strategies to achieve a full integration and verification tool chain are illustrated. The potential of this approach is demonstrated via two different test cases: a lunar landing scenario of the ALINA spacecraft developed by PTS, and CALLISTO reusable rocket demonstrator.

Analytical performance overview of the Lumipulse G pTau 181 Plasma RUO

AbstractBackgroundStudies have shown that changes in Alzheimer’s disease (AD) biomarker levels occur in blood at approximately the same time as in cerebrospinal fluid (CSF). Therefore, plasma‐based testing could be used as a simple, accessible, and scalable approach to help support the diagnosis of AD, avoiding the complexity of CSF sampling, and the high costs and limited availability of PET imaging. It was demonstrated that plasma pTau181 has the potential to be a good predictor of amyloid PET positivity, has proven to differentiate between AD and non‐AD neurodegenerative diseases, and is able to predict progression to AD. The aim of this study was to determine the preliminary analytical performance of the newly developed Lumipulse G pTau 181 Plasma RUO assay.MethodThe LUMIPULSE G System is a chemiluminescent enzyme immunoassay platform that allows fully automated processing of samples using ready‐to‐use immunoreaction cartridges. Time to result in these single use test cartridges takes about 30 minutes. The assay uses AT270 for capturing and HT7/BT2‐conjugate for detection in a 2‐step set‐up. Parameters analysed were precision, sensitivity, linearity, and potential impact of interfering substances. The studies included a series of buffer– and K2EDTA plasma samples at different concentration levels, each tested in several replicates sized to the different parameters tested.ResultThe total within‐lab variability of the assay was found to be <5% CV for each of the samples tested, confirming the high precision of the LUMIPULSE G platform. Using low pTau181 concentrated plasma samples, the LoD was found to be <0.20 pg/mL, and the LoQ <0.50 pg/mL. The high sensitivity was confirmed by a formal concentration assignment to each tested samples of a cohort of healthy elderly subjects. Linearity was shown across the measurement range of the assay (0 – 60 pg/mL), and no significant impact of rheumatoid factor and human anti‐mouse antibodies was observed.ConclusionThis preliminary verification of the analytical performance of the Lumipulse G pTau 181 Plasma RUO indicated promising results in terms of low variability, good dilutional linearity, and high sensitivity. The assay is now ready for full analytical verification and clinical validation towards the identified contexts of use.

Design and preparation of high-performance polymer mortars based on performance prediction model

This article had presented a systematic and adjustable method to forecast the performance of certain type of polymer mortars, most of all, using the performance prediction model to accurately control the dosages of water reducing agent (D WR ), cellulose (D C ), polypropylene fiber (D F ), expansion agent (D EA ), redispersible emulsion powder (D REP ), and cement content (C C ), according to the changes of properties of polymer mortars. The article had given a full verification supported by a series of orthogonal experiment results to demonstrate the effectiveness and the feedback loop between raw materials and properties of polymer mortars, which had revealed a big practical value and convenience for rapid construction in the job sites, especially for researchers and engineers in the field. Its effort to avoid, or at least control the damage of polymer powders to compressive strength of cement mortars. The mix proportion of high-performance polymer mortars (HPMs) was determined as follows, considering the working and mechanical properties: D WR was 0.85 g, D C was 1.05 g, D F was 1.15 g, C C was 42%, D EA was 10 g, and D REP was 20 g. Successfully created HPMs with pumping resistance of just 61.6N, compressive strength of 68.5MPa at 28d.