Initial System Research Articles

Reflectionless pseudospin-1 Dirac systems via Darboux transformation and flat band solutions

This manuscript explores the Darboux transformation employed in the construction of exactly solvable models for pseudospin-one particles described by the Dirac-type equation. We focus on the settings where a flat band of zero energy is present in the spectrum of the initial system. Using the flat band state as one of the seed solutions substantially improves the applicability of the Darboux transformation, for it becomes necessary to ensure the Hermiticy of the new Hamiltonians. This is illustrated explicitly in four examples, where we show that the new Hamiltonians can describe quasi-particles in Lieb lattice with inhomogeneous hopping amplitudes.

Pysanky to Microfluidics: An Innovative Wax-Based Approach to Low Cost, Rapid Prototyping of Microfluidic Devices.

A wax-based contact printing method to create microfluidic devices is demonstrated. This printing technology demonstrates a new pathway to rapid, cost-effective device prototyping, eliminating the use of expensive micromachining equipment and chemicals. Derived from the traditional Ukrainian Easter egg painting technique called "pysanky" a series of microfluidic devices were created. Pysanky is the use of a heated wax stylus, known as a "kistka", to create micro-sized, intricate designs on the surface of an egg. The proposed technique involves the modification of an x-y-z actuation translation system with a wax extruder tip in junction with Polydimethysiloxane (PDMS) device fabrication techniques. Initial system optimization was performed considering design parameters such as extruder tip size, contact angle, write speed, substrate temperature, and wax temperature. Channels created ranged from 160 to 900 μm wide and 10 to 150 μm high based upon system operating parameters set by the user. To prove the capabilities of this technology, a series of microfluidic mixers were created via the wax technique as well as through traditional photolithography: a spiral mixer, a rainbow mixer, and a linear serial dilutor. A thermo-fluidic computational fluid dynamic (CFD) model was generated as a means of enabling rational tuning, critical to the optimization of systems in both normal and extreme conditions. A comparison between the computational and experimental models yielded a wax height of 57.98 μm and 57.30 μm, respectively, and cross-sectional areas of 11,568 μm2 and 12,951 μm2, respectively, resulting in an error of 1.18% between the heights and 10.76% between the cross-sectional areas. The device's performance was then compared using both qualitative and quantitative measures, considering factors such as device performance, channel uniformity, repeatability, and resolution.

Approaches to enhance user experience and satisfaction with the design of the ComplaintCraft system: A study on its features and objectives

The complaint letter is significant in interpersonal communication and feedback. To many individuals, particularly those with limited experience and expertise in letter writing, it remains a significant challenge to effectively express their emotional complexity. Consequently, many individuals choose not to voice their concerns and emotions. To address this issue, we conducted 3 iterations to formulate ComplaintCraftan innovative system that enables users to interactively customize and generate complaint letters with the help of ChatGPT: (i) Conducting a survey with 63 staff members to determine their specific requirements and preferences about complaint letter. (ii) Co-designing a low-fidelity prototype with three students, based on their feedback, gleaning valuable insights, refining interfaces, and sequentially inputting formulation. (iii) Evaluating the user experience of the initial system of ComplaintCraft in different real-world cases with six individuals who intended to file complaints in the near future, gaining detailed insights into which feature in ComplaintCraft is helpful in addressing their real-world issues when composing complaints and what problems exist in the initial system. The initiatives ultimate goal is to enhance the usability of AI writing tools and encourage users to express themselves with confidence.

Structural Identifiability Evaluation of System with Nonsymmetric Nonlinearities

The complexity of objects and control systems increases the requirements for mathematical models. The structural identifiability (SI) assessment of nonlinear systems is one of the identification problems. Until now, this problem solves by parametric methods using various approximation methods. This approach is not always effective under uncertainty. We apply an approach to SI estimation based on the analysis of virtual framework. There is an objects class whose properties describe by nonsymmetric nonlinearities. The paper generalizes and develops the virtual framework (VF) method for systems with asymmetric non-linearities. Requirements for the system input are formed based on the excitation constancy property and S-synchronizability. Considering S-synchronizability gives VF that most fully reflect nonlinear properties of the system. A method for designing virtual structures based on the measurement information analysis describes. Structural identifiability fundamentals described for systems with symmetric nonlinearities. Splitting of the initial nonlinear system obtains for the VF application. Two methods consider for evaluating SI systems with nonsymmetric nonlinearities (NN) and propose their development on systems with nonsymmetric nonlinearities. Virtual framework almost homotheticity conditions obtain for SI estimation. A NN class with parametric features considers and conditions for estimating their almost homotheticity obtain. Conditions of almost homothety and h-identifiability obtain for systems with NN. The detectability and recoverability proofed for virtual frameworks guaranteed the SI estimation under uncertainty. The conditions under which the nonsymmetric nonlinearity is hypothetical symmetric nonlinearity obtained. The described approach to the SI assessment is general. If the SI of specific nonlinear systems analyzes, then features these systems consider. These features require modification of proposed algorithms and procedures. SI evaluation examples of closed nonlinear systems given under uncertainty and of the excitation constancy fulfillment.

Vibration fatigue properties and deterioration mechanism of diffusion bonded TC4 titanium alloy

To analyze the effect of diffusion bonding process on vibration fatigue properties, a series of fatigue tests and microstructure characterization of as-received and diffusion bonded TC4 titanium alloy were conducted. The results show that the thermal cycling of diffusion bonding process results in microscopic change and deteriorates vibration fatigue lifetime of TC4 alloy. For bonded TC4 alloy, the increased grain size inhomogeneity stimulates incompatible deformation of differently oriented α grains and leads to micro-void formation at boundaries of small/large α grain pairs or inside large α grains. Meanwhile, the orientation variation of α grains promotes activation of prismatic slip systems for earlier crack initiation. In addition, the increased fraction of β phase provides more nucleation locations for micro-voids. Thus, the increase of the grain size inhomogeneity, grain orientation change, and the increase of β phase fraction due to the thermal cycling result in fatigue performance deterioration of diffusion bonded TC4 titanium alloy.

Explicit dynamical systems on the Sierpiński carpet

We apply Boroński and Oprocha’s inverse limit construction of dynamical systems on the Sierpiński carpet by using the initial systems of n-Chamanara surfaces and their n-baker transformations, n≥2. We show that all positive real numbers are realized as metric entropy values of dynamical systems on the carpet. We also produce a simplification of Boroński and Oprocha’s proof showing that dynamical systems on the carpet do not have the Bowen specification property.

Optimal planning of urban air mobility systems accounting for ground access trips

The concept of Urban Air Mobility (UAM), an on-demand aviation service using air vehicles for urban short-distance trips, such as electric vertical takeoff and landing aircraft (eVTOL), has recently drawn public attention as one of possible solutions to traffic congestion in metropolitan areas. We present an optimal planning framework for fleet size and vertiport numbers using generalized cost models of UAM trip chains with two different ground access modes for first and last mile trips, including taxis and robotaxis (i.e. autonomous taxis or shared autonomous vehicles). As it is a relatively new and untested mode of transportation, our research aims to provide a decision-making tool for initial UAM system planning and analysis of its economic feasibility, appropriately considering its unique characteristics, such as high free-flow speed, low circuity, needs for ground access, and specific cost factors, such as vertiport and electric vertical takeoff and landing aircraft costs. Through a parametric study, we quantitatively examine the necessary conditions for UAM, with or without ridesharing, to become more economically viable than other ground-only modes. The study confirms that UAM can have potential economic benefits especially in large cities with longer average trip lengths and severe traffic congestion, where the average ground vehicle speed is low.

The role of initial system–environment correlations with a spin environment

Open quantum systems are a subject of immense interest as their understanding is crucial in the implementation of modern quantum technologies. In the study of their dynamics, the role of the initial system–environment correlations is commonly ignored. In this work, to gain insights into the role of these correlations, we solve an exactly solvable model of a single two-level system interacting with a spin environment, with the initial system state prepared by a suitable unitary operation. By solving the dynamics exactly for arbitrary system–environment coupling strength while taking into account the initial system–environment correlations, we show that the effect of the initial correlations is, in general, very significant and nontrivial. To further highlight the importance of the initial system–environment correlations, we also extend our study to investigate the dynamics of the entanglement between two two-level systems interacting with a common spin environment.

Simplified design method for optical imaging systems based on aberration characteristics of optical-digital joint optimization.

With the continuous improvement of imaging performance requirements, the design of imaging systems has become increasingly complex, making it more difficult and expensive to manufacture and test. To overcome these problems, a simplified design framework for imaging systems based on aberration characteristics of optical-digital joint optimization was built in this paper. Specifically, an improved total variation regularization restoration algorithm was proposed, and the difficulty of correction for different monochromatic aberrations was evaluated. With this evaluation, the proposed algorithm was combined with the traditional optical design method to jointly correct the aberration and simplify the optical system by relaxing the requirements for optical structures and surface shapes under the guarantee of the imaging performance. To demonstrate the feasibility and efficiency of the method, three design examples are provided, where the structure similarity index measure of the simulation imaging results is on the same level as that of the initial system, with a maximum error not exceeding 0.04. The simulation results demonstrate that our design method can effectively simplify the optical structure of imaging systems while maintaining high performance.

From femtoseconds to minutes: time-resolved macromolecular crystallography at XFELs and synchrotrons.

Over the last decade, the development of time-resolved serial crystallography (TR-SX) at X-ray free-electron lasers (XFELs) and synchrotrons has allowed researchers to study phenomena occurring in proteins on the femtosecond-to-minute timescale, taking advantage of many technical and methodological breakthroughs. Protein crystals of various sizes are presented to the X-ray beam in either a static or a moving medium. Photoactive proteins were naturally the initial systems to be studied in TR-SX experiments using pump-probe schemes, where the pump is a pulse of visible light. Other reaction initiations through small-molecule diffusion are gaining momentum. Here, selected examples of XFEL and synchrotron time-resolved crystallography studies will be used to highlight the specificities of the various instruments and methods with respect to time resolution, and are compared with cryo-trapping studies.

Grafting Starch with Acrylic Acid and Fenton's Initiator: The Selectivity Challenge.

Through the graft polymerization of acrylic monomers onto starch, materials with interesting new properties can be synthesized. Fenton's chemistry, Fe2+/H2O2, is considered to be attractive for the initiation of graft polymerization with the monomer acrylic acid since it is cheap and reacts quickly at ambient conditions and should therefore be easy to scale up. However, the selectivity of the grafting versus the homopolymerization reaction poses a challenge with this monomer and this type of initiator. In the present review paper, we investigate why data from the literature on grafting systems with other monomers and initiation systems tend to show higher graft selectivity. A scheme is presented, based on reaction engineering principles, that supports an explanation for these observed differences. It is found that more selective activation of starch is a factor, but perhaps even more important is a low monomer-to-starch ratio at the starting sites of graft reactions. Since water is the most common solvent, monomers that are less water-soluble have an advantage in this respect. Based on the proposed scheme, methods to improve the graft selectivity with Fenton's initiator and acrylic acid are evaluated. Most promising appears to be a method of gradual monomer dosage. With gelatinized cassava starch in a batch reactor, both the grafting percentage (17 => 29%) and graft selectivity (18 => 31%) could be improved. This can be considered a principal breakthrough. Still, more research and development would be needed to refine the method and to implement the idea in a continuous reactor at a larger scale.

Design and FPGA implementation of a hyperchaotic conservative circuit with initial offset-boosting and transient transition behavior based on memcapacitor

A charge-controlled memcapacitive conservative chaotic circuit with trigonometric function terms is constructed in this paper. By analyzing the characteristics of the infinite equilibrium point and the divergence of the system, it is proved that the system is conservative. Under the influence of system parameters, hyperchaotic and chaotic characteristics can be switched to each other. With the increase of parameters and initial values, the Lyapunov exponent is also greatly improved. In addition, the transient chaos phenomenon accompanied by the internal crisis is also found, which leads to the sudden change of the orbit state of the attractor, and different types of coexisting attractors in different regions of the basins are also found. Through further analysis of the phase diagram, bifurcation diagram and time-domain waveform, it is found that there are three initial offset-boosting behaviors with different characteristics in the system. Finally, the spectral entropy (SE) algorithm is used to compare the memcapacitive circuit complexity under different initial conditions and system parameters. We find that the SE complexity distribution map is consistent with the Lyapunov exponent trajectory, which further reflects the influence of system parameters and initial conditions on the dynamic characteristics of the system. On the platform of Cyclone IV E series, the FPGA main chip of EP4CE10F17C8N is used to complete the hardware implementation of the system. The FPGA implementation results are consistent with numerical simulation, and verify the realistic feasibility of the memcapacitive conservative chaotic circuit in practical application.

Stabilizability of multi-agent systems under event-triggered controllers

In view of the problems of large consumption of communication and computing resources in the control process, this paper studies a fundamental property for a class of multi-agent systems under event-triggered strategy: the S-stabilizability of a group of multi-agent systems with general linear dynamics under weakly connected directed topology. The results indicate that the S-stabilizability can be described in some way that the stabilizability region and feedback gain can evaluate the performance of the protocol. Firstly, a new distributed event-triggered protocol is proposed. Under this protocol, a kind of hybrid static and dynamic event-triggered strategy are presented, respectively. In particular, by using Lyapunov stability theory and graph partition tool, it is proved that the proposed event-triggered control strategy can guarantee the closed-loop system achieve S-stabilizability effectively, if at least one vertex in each iSCC (independent strongly connected component) cell receives information from the leader, which reflects the ability of distributed control law. Further, we demonstrate that the stabilizability can be realized if the initial system matrix A is Hurwitz. Moreover, it is confirmed that the designed static event-triggered condition is a limit case of dynamic event condition and can guarantee Zeno-free behavior. Finally, the validity of the theoretical results is proved by numerical simulation.

Robust fixed-time fault-tolerant control for unmanned marine vehicles via integral terminal sliding mode technique

In this paper, a novel fixed-time fault-tolerant control (FTC) scheme is proposed for unmanned marine vehicles (UMVs) with dynamics uncertainties and ocean disturbances. By introducing a high-order integral term, a fixed-time integral terminal sliding mode (ITSM) with faster convergence rate is proposed, which mitigates the effect of the initial system state on the convergence time successfully. Furthermore, based on the online estimation information from the adaptive mechanism, the effects of thruster faults, dynamics uncertainties, and ocean disturbances can be compensated by designing an adaptive fixed-time fault-tolerant controller. Compared to the existing results, the proposed FTC strategy ensures stability in a fixed-time framework. Finally, the comparison simulations of a floating production ship have demonstrated the efficacy of the proposed scheme.

High-efficiency pentafluorostilbene-based photocatalysts dedicated to preparing fluorescent 3D printed polymer nanocomposites

ABSTRACT The following manuscript describes 10 newly synthesised pentafluorostilbene derivatives that are diverse in the character of the substituent attached to the second phenyl ring, as well as in the substitution site. The compounds were investigated for their applicability as iodonium salt photosensitisers for initiating cationic, radical and hybrid photopolymerisation. For this purpose, various spectroscopic studies were performed, such as absorbance and fluorescence quenching experiments. For kinetic research, Fourier transform infrared spectroscopy (real-time FT-IR) was utilised, which enabled analysis of the performance of the investigated two-component photoinitiating systems in real time. According to a variety of kinetic studies, the most effective initiator system was selected and applied for application studies in the subsequent stage, namely the preparation of photocurable polymer nanocomposites using light-initiated 3D printing technology (DLP – Digital Light Processing). The most effective two-component initiating system was tested in seven different photo-curable resins by thermogravimetry (TGA) and dynamic mechanical analysis (DMA) to demonstrate its applicability in 3D printing of nanocomposites.

Skeleton-based coordinate system construction method for non-cooperative targets

Due to the lack of structure and part information in non-cooperative targets, the task of pose estimation suffers from unstable and unreliable initial coordinate system. In this paper, we introduce a curve-skeleton-based method to construct the robust coordinate system automatically for non-cooperative targets. First, a nonmanifold-Laplacian-based method is proposed to extract the curve skeleton from point clouds. The proposed method solves the over-contraction problem while preserves the topology and structure of skeleton well during point clouds contraction. Additionally, we create the skeleton graph to detect the skeleton structure and key points automatically. Then, the detected skeleton feature is used to construct target coordinate system, and improve the stability and robustness. Specifically, a real-scan dataset is constructed in this paper, and the proposed point cloud contraction method outperforms previous methods in structural representation and visualization. The mean rotation error of proposed coordinate system construct method performs 0.1249° and 1.2135° in 0%–30% noise ratio of distortions and outliers, and performs 7.04° and 4.21° in real-scan aircraft and satellite datasets. The results in complete and incomplete datasets verify the robustness and reliability of our skeleton-based coordinate system.

DARTS: an open-source Python pipeline for Ca2+ microdomain analysis in live cell imaging data.

Ca2+ microdomains play a key role in intracellular signaling processes. For instance, they mediate the activation of T cells and, thus, the initial adaptive immune system. They are, however, also of utmost importance for activation of other cells, and a detailed understanding of the dynamics of these spatially localized Ca2+ signals is crucial for a better understanding of the underlying signaling processes. A typical approach to analyze Ca2+ microdomain dynamics is live cell fluorescence microscopy imaging. Experiments usually involve imaging a larger number of cells of different groups (for instance, wild type and knockout cells), followed by a time consuming image and data analysis. With DARTS, we present a modular Python pipeline for efficient Ca2+ microdomain analysis in live cell imaging data. DARTS (Deconvolution, Analysis, Registration, Tracking, and Shape normalization) provides state-of-the-art image postprocessing options like deep learning-based cell detection and tracking, spatio-temporal image deconvolution, and bleaching correction. An integrated automated Ca2+ microdomain detection offers direct access to global statistics like the number of microdomains for cell groups, corresponding signal intensity levels, and the temporal evolution of the measures. With a focus on bead stimulation experiments, DARTS provides a so-called dartboard projection analysis and visualization approach. A dartboard projection covers spatio-temporal normalization of the bead contact areas and cell shape normalization onto a circular template that enables aggregation of the spatiotemporal information of the microdomain detection results for the individual cells of the cell groups of interest. The dartboard visualization allows intuitive interpretation of the spatio-temporal microdomain dynamics at the group level. The application of DARTS is illustrated by three use cases in the context of the formation of initial Ca2+ microdomains after cell stimulation. DARTS is provided as an open-source solution and will be continuously extended upon the feedback of the community. Code available at: 10.5281/zenodo.10459243.

COMPARISON OF DEGENERATIVE MRI FEATURES OF THE INTERVERTEBRAL DISC BETWEEN THOSE WITH AND WITHOUT CHRONIC LOW BACK PAIN: AN EXPLORATORY STUDY OF TWO LARGE FEMALE POPULATIONS USING AUTOMATED ANNOTATION

The relationship of degeneration to symptoms has been questioned. MRI detects apparently similar disc degeneration and degenerative changes in subjects both with and without back pain. We aimed to overcome these problems by re-annotating MRIs from asymptomatic and symptomatic groups onto the same grading system.We analysed disc degeneration in pre-existing large MRI datasets. Their MRIs were all originally annotated on different scales. We re-annotated all MRIs independent of their initial grading system, using a verified, rapid automated MRI annotation system (SpineNet) which reported degeneration on the Pfirrmann (1-5) scale, and other degenerative features (herniation, endplate defects, marrow signs, spinal stenosis) as binary present/absent. We compared prevalence of degenerative features between symptomatics and asymptomatics.Pfirrmann degeneration grades in relation to age and spinal level were very similar for the two independent groups of symptomatics over all ages and spinal levels. Severe degenerative changes were significantly more prevalent in discs of symptomatics than asymptomatics in the caudal but not the rostral lumbar discs in subjects < 60 years. We found high co-existence of degenerative features in both populations. Degeneration was minimal in around 30% of symptomatics < 50 years.We confirmed age and disc level are significant in determining imaging differences between asymptomatic and symptomatic populations and should not be ignored. Automated analysis, by rapidly combining and comparing data from existing groups with MRIs and information on LBP, provides a way in which epidemiological and ‘big data’ analysis could be advanced without the expense of collecting new groups.

Persistency of tripartite nonlocality sharing with noise

Recently, researchers have proven that an infinite number of Charlies and a pair of Alice and Bob can share standard tripartite nonlocality and genuinely nonsignal nonlocality by violating the Mermin and NS inequalities within tripartite systems. This discovery undoubtedly provides new perspectives and potential in quantum information science. However, it should be noted that the above-mentioned conclusion is derived on the highly idealized assumption that the quantum system is perfect and free from external disturbances. In reality, the realization of this ideal state is a challenging proposition. As a fundamental aspect of quantum mechanics, the phenomenon of quantum entanglement is susceptible to the influence of external factors, such as noise, during its practical implementation. Additionally, the process of quantum measurement can introduce potential errors, which may potentially diminish or even negate the observed quantum nonlocality. In light of the above situation, we investigate whether it is possible to share the corresponding quantum nonlocality, despite the inevitable occurrence of noise and error. This paper aims to study and discuss the persistency of nonlocality in noisy three-qubit systems. Firstly, the sufficient conditions are provided for Alice and Bob to share standard tripartite nonlocality with any number of Charlies, even when measurements are noisy and the initial three-qubit system is in a maximally entangled state with noise. This finding indicates that certain standard tripartite nonlocality can persist under non-ideal conditions as long as certain conditions are met. Moreover, this article elucidates the necessary conditions for multiple independent Charlies to share genuinely nonsignal nonlocality with a pair of Alice and Bob in a non-ideal state. This implies that despite the presence of noise and errors, this type of genuinely nonsignal nonlocality can still be securely shared among multiple parties as long as specific conditions are met. This research provides a new theoretical basis for the security and feasibility of quantum communication. The comprehensive analysis presented in this paper offers insights into the behavior of triple quantum nonlocality under noiseless conditions.

Designing sustainable mobile weight management applications: information technology (IT) experts perspectives.

Weight management mobile applications have become increasingly popular as a tool for individuals to achieve their weight loss goals. However, key challenges with mobile weight management applications are sustaining user engagement and promoting long-term behavior change. This study examines the key functions and features of weight management mobile applications from the viewpoint of information technology (IT) experts. We have developed a framework that outlines the optimal design strategies for mobile apps to support sustainable weight management. We conducted face-to-face interviews with five experts to evaluate and give input on the proposed framework. Eight specialized functionalities have been categorized and defined based on initial framework system features and recommended features based on experts' feedback: (I) customization; (II) usability; (III) integration; (IV) online support; (V) tracking; (VI) nutrition database; (VII) gamification; and (VIII) notification. In addition, common functionalities were identified as (I) registration/sign in; (II) data privacy; (III) security; and (IV) user feedback. An online discussion indicates the system functionality in four themes: (I) configuration; (II) data analytics; (III) support/performance; and (IV) platform: iOS, Android, Native. These functionalities and features will be incorporated into a framework to design mobile applications for sustainable weight management. Also, to be part of user interface development for the user experience experiments.