Position Swapping Research Articles

Motion planning of multiple unmanned vehicles using sequential convex programming‐based distributed model predictive control

AbstractThis article tackles the complex challenge of multi‐vehicle motion planning by presenting the novel Sequential Convex Programming‐based Distributed Model Predictive Control (SCP‐DMPC) algorithm. Existing methods often struggle with the nonconvex nature of optimization in multi‐vehicle motion planning, frequently compromising on computational efficiency. SCP‐DMPC innovatively combines the predictive control of DMPC with the optimization prowess of SCP to address these issues efficiently, while adhering to both physical and operational constraints. To ensure precise attainment of target poses, a three‐stage control strategy is introduced, with theoretical analysis on its recursive feasibility and asymptotic stability, enhancing the reliability of the algorithm. Moreover, a heuristic‐based deadlock resolution scheme is devised to prevent vehicle stalling, a common issue in cooperative motion. Validated through simulations in challenging scenarios, including symmetric position swapping and obstacle‐laden formation transition, SCP‐DMPC demonstrates superior adaptability, precision, and efficiency. These results underscore its potential for robust, real‐time unmanned vehicle applications, suggesting new directions for future research and development in the field.

Quantum data visualization: A quantum computing framework for enhancing visual analysis of data

Data visualization assists in the evaluation and analysis of large graphical data sets. In this study, quantum data visualization (QDV) is proposed as the first attempt to aid users in more effectively comprehending data via quantum mechanical effects. The QDV framework is introduced to fully illustrate the steps necessary for implementing this novel concept. To provide a more intuitive visual representation for data analysis, the quantum rendering module is established to associate quantum data with color gradient information based on continuous geometric primitives in QDV tools. As an application, 2D and 3D QDV tools are designed and applied, including quantum circuit diagrams for preparing pie charts, scatter plots, bar graphs, and function curves. Moreover, the interaction mechanisms used to perform scaling, numerical calculations, and position swapping operations on geometric primitives are discussed and demonstrated. In analyzing QDV efficiency, evaluation metrics, such as cost, delay, width, and auxiliary qubit quantities, were calculated for key quantum processes, to assess framework performance and illustrate corresponding advantages over conventional data visualization models.

Efficient Qubit Routing for a Globally Connected Trapped Ion Quantum Computer

AbstractThe cost of enabling connectivity in noisy intermediate‐scale quantum (NISQ) devices is an important factor in determining computational power. A qubit routing algorithm is created, which enables efficient global connectivity in a previously proposed trapped ion quantum computing architecture. The routing algorithm is characterized by comparison against both a strict lower bound, and a positional swap based routing algorithm. An error model is proposed, which can be used to estimate the achievable circuit depth and quantum volume of the device as a function of experimental parameters. A new metric based on quantum volume, but with native two‐qubit gates, is used to assess the cost of connectivity relative to the upper bound of free, all to all connectivity. The metric is also used to assess a square‐grid superconducting device. These two architectures are compared and it is found that for the shuttling parameters used, the trapped ion design has a substantially lower cost associated with connectivity.

Arginine-lysine positional swap of the LL-37 peptides reveals evolutional advantages of the native sequence and leads to bacterial probes

Antimicrobial peptides are essential components of the innate immune system of multicellular organisms. Although cationic and hydrophobic amino acids are known determinants of these amphipathic molecules for bacterial killing, it is not clear how lysine-arginine (K-R) positional swaps influence peptide structure and activity. This study addresses this question by investigating two groups of peptides (GF-17 and 17BIPHE2) derived from human cathelicidin LL-37. K-R positional swap showed little effect on minimal inhibitory concentrations of the peptides. However, there are clear differences in bacterial killing kinetics. The membrane permeation patterns vary with peptide and bacterial types, but not changes in fluorescent dyes, salts or pH. In general, the original peptide is more efficient in bacterial killing, but less toxic to human cells, than the K-R swapped peptides, revealing the evolutionary significance of the native sequence for host defense. The characteristic membrane permeation patterns for different bacteria suggest a possible application of these K-R positional-swapped peptides as molecular probes for the type of bacteria. Such differences are related to bacterial membrane compositions: minimal for Gram-positive Staphylococcus aureus with essentially all anionic lipids (cardiolipin and phosphatidylglycerol), but evident for Gram-negative Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli with a mixture of phosphatidylethanolamine and phosphatidylglycerol. Biophysical characterization found similar structures and binding affinities for these peptides in vesicle systems mimicking E. coli and S. aureus. It seems that interfacial arginines of GF-17 are preferred over lysines in bacterial membrane permeation. Our study sheds new light on the design of cationic amphipathic peptides.

Distinct 3D Architecture and Dynamics of the Human HtrA2(Omi) Protease and Its Mutated Variants.

HtrA2(Omi) protease controls protein quality in mitochondria and plays a major role in apoptosis. Its HtrA2S306A mutant (with the catalytic serine routinely disabled for an X-ray study to avoid self-degradation) is a homotrimer whose subunits contain the serine protease domain (PD) and the regulatory PDZ domain. In the inactive state, a tight interdomain interface limits penetration of both PDZ-activating ligands and PD substrates into their respective target sites. We successfully crystalized HtrA2V226K/S306A, whose active counterpart HtrA2V226K has had higher proteolytic activity, suggesting higher propensity to opening the PD-PDZ interface than that of the wild type HtrA2. Yet, the crystal structure revealed the HtrA2V226K/S306A architecture typical of the inactive protein. To get a consistent interpretation of crystallographic data in the light of kinetic results, we employed molecular dynamics (MD). V325D inactivating mutant was used as a reference. Our simulations demonstrated that upon binding of a specific peptide ligand NH2-GWTMFWV-COOH, the PDZ domains open more dynamically in the wild type protease compared to the V226K mutant, whereas the movement is not observed in the V325D mutant. The movement relies on a PDZ vs. PD rotation which opens the PD-PDZ interface in a lid-like (budding flower-like in trimer) fashion. The noncovalent hinges A and B are provided by two clusters of interfacing residues, harboring V325D and V226K in the C- and N-terminal PD barrels, respectively. The opening of the subunit interfaces progresses in a sequential manner during the 50 ns MD simulation. In the systems without the ligand only minor PDZ shifts relative to PD are observed, but the interface does not open. Further activation-associated events, e.g. PDZ-L3 positional swap seen in any active HtrA protein (vs. HtrA2), were not observed. In summary, this study provides hints on the mechanism of activation of wtHtrA2, the dynamics of the inactive HtrA2V325D, but does not allow to explain an increased activity of HtrA2V226K.

Analysis of Silicon Based Surface Plasmon Resonance Sensors with Different Amino Acids

A semiconductor prism coupler based nano-plasmonic sensor consisting of a high refractive index (RI) silicon prism, a gold (Au) metal film and different amino acids was used as a dielectric sample for sensing in the in the Attenuated Total Internal Reflection (ATIR) mode. An additional silicon nano-layer has been used for increasing stability and sensitivity of the surface plasmon resonance-sensor which causes enhancement of the evanescent field near the metal-analyte interface compared to the traditional three layer structure. Positional swap of the silicon nano-layer from above the metal surface to below the metal surface causes further enhances of the evanescent field near the metal-analyte interface. Performance of the nano-plasmonic sensors depending upon the high refractive index silicon prism, additional silicon nano-layer and swapping mechanism is discussed with the help of sensing performance for different amino acids with corresponding image response for the proposed nano-plasmonic sensor in a MATLAB environment.

Algorithm for Text Data Encryption by Position Swapping based on LFSR Pseudorandom Key Generation

Data security is one of the main issues as the technology is rising. Daily infinite amount of data is being transmitted over the internet, through mobile phones, laptops, and it is of more concern that, that data should be secured. Cryptography gives us number of ways by which the security can be enhanced. Number of encryption algorithms and protocols are there, by which the data can be made more and more secure. Cryptography is the science where security engineering meets mathematics. In this paper, a basic two level encryption algorithm has been proposed based on the position swapping of data values according the values of key and LFSR pseudorandom sequence generation for making the transmission of text data secure.

Circular Phase Response-Based Analysis for Swapped Multilayer Metallo-Dielectric Plasmonic Structures

In this paper, two types of nanoplasmonic structures, namely multilayer metallo-dielectric and multilayer-swapped metallo-dielectric structures have been analyzed in context of phase jumps and related phenomena due to the positional swap in the metallo-dielectric block. Phase, reflectivity, and field enhancement plots are also discussed in the angular and wavelength regime. Detailed analysis using circular phase response along with the angled histogram of the phase for both structures provides significant understanding of this swapping phenomenon. Parametric analysis of the metallo-dielectric block has also been demonstrated. Figure of merit defined in complex plane also gives some insight into the performance of the structures.

The contributions of confusion and position swapping to crowding between letter-like symbols: Evidence and a Confusion-and-Position-Swapping model

Most current explanations of visual crowding are descriptive. Greenwood et al. (2009, 2010) built a feature position average (FPA) model to explain crowding with letter-like symbols. Here we used crowding errors observed with a similar experimental paradigm to compare this and an alternative model. A T target in one of four cardinal orientations 12.5° above the fixation was paired with a flanker which was one of 25 "cross-like" symbols (including four Ts). The target and flanker had four configurations (flanker on the top, bottom, left, or right side of the target). Observers reported the T target orientation. T target identification rate was 92.3% when presented alone and 68.2% when accompanied by a flanker. When the target and flanker were both Ts, 62.7% of the errors were the flanker being reported as the target. When the flanker was a No-T symbol, a T symbol that was more confusable to the flanker than to the target was often reported, accounting for 50-70% of errors across stimulus configurations. A confusion and position swapping (CPS) model was thus built in which a No-T flanker was allowed first to be misperceived as a T symbol according to an empirical confusion rate and then to swap position with the target at a to-be-determined rate, PSR, the only model parameter. Greenwood’s three-parameter FPA model was also tested. The correlations between observed and model generated errors were 0.442 and 0.604 for FPA and CPS, respectively, suggesting the CPS model being able to better explain the experimental data. The best-fitting PSRs of the CPS model were 0.33, 0.21, 0.28 and 0.27 for the top, bottom, left, and right flanker configurations, respectively indicating the strongest and weakest symbol-level position swapping with outer and inner flankers, respectively, and average swapping when the target and flanker were equal distance from the fovea. Meeting abstract presented at VSS 2012

Whole report uncovers correctly identified but incorrectly placed target information under visual crowding

Multiletter identification studies often find correctly identified letters being reported in wrong positions. However, how position uncertainty impacts crowding in peripheral vision is not fully understood. The observation of a flanker being reported as the central target cannot be taken as unequivocal evidence for position misperception because the observers could be biased to report a more identifiable flanker when failing to identify the central target. In addition, it has never been reported whether a correctly identified central target can be perceived at a flanker position under crowding. Empirical investigation into this possibility holds the key to demonstrating letter-level position uncertainty in crowding, because the position errors of the least identifiable central target cannot be attributed to response bias. We asked normally-sighted observers to report either the central target of a trigram (partial report) or all three characters (whole report). The results showed that, for radially arranged trigrams, the rate of reporting the central target regardless of the reported position in the whole report was significantly higher than the partial report rate, and the extra target reports mostly ended up in flanker positions. Error analysis indicated that target-flanker position swapping and misalignment (lateral shift of the target and one flanker) underlay this target misplacement. Our results thus establish target misplacement as a source of crowding errors and ascertain the role of letter-level position uncertainty in crowding.

Full Report Uncovers Correctly Identified but Incorrectly Positioned Target Information under Visual Crowding

Current models attribute visual crowding to feature pooling, limited attentional resolution, and flanker substitution that compromise the identity of the target flanked by additional objects. An untested hypothesis is that the flankers may sometimes only disturb the target's perceived position, not its identity, which also causes report errors. To test this hypothesis, observers were asked to report either the central target of a three-letter string (partial report), or all letters (full report), in alternating blocks of trials. In full report, the rate of reporting the central target to the central position was comparable to that in partial report. Importantly, there was also a significant rate of reporting the correct target identity but at a wrong flanker position, supporting our hypothesis. Error analyses indicated that target-flanker position swapping and misalignment underlay observed target misplacement. In addition, target misplacement was only significant in radial, but not tangential, stimulus orientations, and could be observed at both short and long durations. Our results thus suggest a new and previously unknown crowding mechanism that interferes with the perceived position of a correctly identified target. The new mechanism, along with previously revealed ones that impair target identity, provides a more comprehensive account of visual crowding.

Position swapping and pinching in Bose-Fermi mixtures with two-color optical Feshbach resonances

We examine the density profiles of the quantum degenerate Bose-Fermi mixture of $^{174}\mathrm{Yb}$-$^{173}\mathrm{Yb}$, experimentally observed recently, in the mean-field regime. In this mixture there is a possibility of tuning the Bose-Bose and Bose-Fermi interactions simultaneously using two well-separated optical Feshbach resonances, and it is a good candidate to explore phase separation in Bose-Fermi mixtures. Depending on the Bose-Bose scattering length ${a}_{\mathrm{BB}}$, as the Bose-Fermi interaction is tuned the density of the fermions is pinched or swapping with bosons occurs.

Classical and quasi-classical trajectory calculations of isotope exchange and ozone formation proceeding through O+O2 collision complexes

The isotope exchange reaction, and the three-body ozone formation rate proceeding through an ozone complex, have been studied by classical and quasi-classical trajectory techniques. The exchange rate studies indicate that the rate of this reaction is dominantly sensitive to the O+O2 entrance channel characteristics of the potential energy surface. A detailed consideration of the dynamics of the intermediate ozone complex reveals three important classes. In one class, the complex adopts an ozonelike geometry, largely undergoing asymmetric stretchinglike motion until it dissociates. In a second class, the oxygen atom and molecule never visit the ozonelike geometry but rather remain separated by relatively large distances trapped near the angular momentum barrier in the entrance channel of a pseudo-effective potential. These complexes, which cannot undergo exchange, are, nevertheless, found to contribute significantly to ozone formation at high density of the third body suggesting that the association of the high-density effective formation rate constant with twice the exchange rate may not be valid. The third class can be considered a hybrid of the first two, spending some time as an ozonelike complex and some time as a large atom-diatomic complex. This third class provides a mechanism for rearranging atom locations in the complex (e.g., end and middle position swapping) and, consequently, would not be well accounted for by statistical treatments of the ozone complex based on a single ozonelike reference geometry. In general, the survival time distributions of the complexes are found to be nonexponential. However, when the detailed survival time distributions are coupled with a Lennard-Jones collision model for the stabilization step, the experimental ozone formation rate can be adequately modeled over a broad range of temperature and density.

Mutagenesis of Segment 487Phe-Ser-Arg-Asp-Arg-Lys492 of Sarcoplasmic Reticulum Ca2+-ATPase Produces Pumps Defective in ATP Binding

The lysine residue Lys492 located in the large cytoplasmic domain of sarcoplasmic reticulum Ca2+-ATPase is implicated in nucleotide binding through affinity labeling. The contribution of segment 487Phe-Ser-Arg-Asp-Arg-Lys492 to ATP binding and pump function has been investigated through the introduction of 11 site-directed amino acid mutations. ATP binding was measured through competitive inhibition of [gamma-32P]2',3'-O-(2,4, 6-trinitrophenyl)-8-azido-adenosine triphosphate photolabeling of Lys492 or its substitute. Mutations F487S and positional swap F487S/S488F produced pumps that were severely defective in ATP binding (KD > 1 mM), and mutant F487S, together with F487E, exhibited low ATPase activity and low ATP-supported calcium transport and phosphorylation and failed to show CrATP-dependent Ca2+ occlusion. Mutations F487L, R489L, and K492Y were less inhibitory to ATP binding (KD = 8-49 microM) and, together with K492L and R489D/D490R, produced correspondingly smaller changes in ATP-mediated activities. The ATP dependence of ATPase activity of these five mutants showed deviations from the wild-type profile in the low, intermediate, and high concentration ranges, suggesting defects in ATP-dependent conformational changes. Mutations S488A and D490A had no effect on ATP binding (KD = 0.4 microM) or ATP-mediated activities. None of the mutations significantly affected phosphorylation from Pi or acetyl phosphate-supported Ca2+ transport. Mutations F487L and F487S, and not those at residue 492, increased the K0.5 for Ca2+ activation of transport 2- and 8-fold, respectively. The results implicate Phe487, Arg489, and Lys492 in binding ATP in both a catalytic and a regulatory mode.