Relative Trajectory Research Articles

A New Architecture Paradigm for Tool Wear Prediction during AISI 9840 Drilling Operation

In conventional machining processes based on the chip removal mechanism, the progressive wear of the tool determines a change of the geometric characteristics of the cutting edge. Tool wear is a complex phenomenon and related tool life depends on several factors, such as cutting parameters, lubrication, and tool-workpiece relative trajectories. Tool wear progression affects the quality of the machined parts, making the tool replacement necessary even before its breakage. Moreover, in industrial practice, tool replacement cannot depend on the subjectivity of the operator, thus, the definition of an optimized strategy for cutting tool wear monitoring before tool failure is mandatory. This work compares Random Forest and Neural Network models for predicting tool wear in drilling. For the development of predictive models, tool life tests were performed by drilling through holes on AISI 9840 steel parts, with a coated tungsten carbide drill of 8 mm of diameter and by using constant cutting parameters. Flank wear of the tool was monitored. A set of statistical features computed from the vibration signals, the acoustic emission signals, the power signals and the torque signals constitute the input of the algorithms. The classification accuracy was 88% and 91% for Neural Network and Random Forest models respectively. In order to correctly define the tool replacement policy during production, the developed Random Forest model has been implemented in an industry, through production management software, achieving promising results.

МЕТОДИКА КОНТРОЛЬНОГО ТЕСТИРОВАНИЯ ПРИ ИССЛЕДОВАНИИ ВЛИЯНИЯ «СУХОЙ» ИММЕРСИИ НА ПАРАМЕТРЫ ВЫПОЛНЕНИЯ ЗРИТЕЛЬНО-МОТОРНОЙ ЗАДАЧИ

Effects of reduced support, tactile and proprioceptive afferentation on mapping and manual operating the joystick were evaluated with participation of 14 female subjects. The idea was to compare performance of a 15 minute motor-ocular task in the conditions of dry immersion and lying supine on a couch. The subjects were to direct the pointer from the screen center to one of 8 randomly emerging targets. Pointer coordinates and emergence scenarios were registered; time to reach the target and geometry of pointer trajectories were calculated. Comparison was made by 4 characteristics: latent time of reaction, time of implementing the reaction, relative trajectory length, and averaged precision of trajectory to a target and the sum of trajectories. It was found that despite some individual differences, for all participants these 4 characteristics, equally of moving to a specific target or the sum of targets, were essentially similar. The results attest to the applicability of testing supine subject's manual tracking of the pointer to a target as a baseline data collection in dry immersion experiments aimed to define whether support-deprivation impacts effectiveness of manual moving the pointer to target.

The influence of postoperative morbidity on medium to long-term quality of life trajectories following cytoreductive surgery for peritoneal malignancy – A prospective cohort study

PurposeCytoreductive surgery (CRS) improves survival of selected patients with peritoneal malignancy. However, postoperative morbidity rates remain high. The aim of this study was to determine the impact of postoperative morbidity on the quality of life (QOL) trajectories of patients undergoing CRS. MethodsThis prospective cohort study included consecutive patients undergoing CRS for peritoneal malignancy between April 2017 and March 2023. QOL measures were collected at baseline, pre-discharge, 3, 6, 12, 18 and 24 months postoperatively using the short-form 36 (SF-36v2) survey. Postoperative in-hospital complications were defined according to the Clavien-Dindo Classification. Differences in QOL trajectories for patients with, and without, postoperative complications, length of stay (short versus long) were determined using mixed effects analyses. ResultsA total of 368 patients were included. Mean age was 55 years and 56.2% were female. The main indications for CRS were colorectal peritoneal metastases (46.9%) and appendix adenocarcinoma (23.9%). Overall, QOL decreased sharply from baseline to pre-hospital discharge, returning to baseline 6 to 12 months post-surgery. Severity of postoperative complication and longer length of stay were the main factors negatively impacting physical component trajectories. Postoperative complication, severity of complication and longer length of stay negatively influenced mental component scores, mostly at pre-discharge. ConclusionsQOL following CRS returns to baseline levels within 6 to 12 months. Postoperative morbidity was associated with poorer health related QOL trajectories. Interventions aimed at reducing postoperative morbidity and targeted support may enhance long-term QOL outcomes.

Robustness analysis and station-keeping control of an interferometer formation flying mission in low Earth orbit

The impact of formation flying on interferometry is growing over the years for the potential performance it could offer. However, it is still an open field, and many studies are still required. This article presents the basic principles behind interferometry focusing first on a single array and secondly on a formation of satellites. A sensitivity analysis is carried out to evaluate how the performance of the interferometry is affected by an error in the relative position in the formation geometry. This is estimated by computing the loss of the performance in terms of percentage deviation due to a non-nominal relative trajectory, including two-dimensional errors and defining a payload index. The main goal of this study is to estimate whether some errors in the relative state are more impacting than others. The final objective is to compute the link between a position error and a specific loss of performance, to foresee the origin of the the error. Furthermore, a dynamical model is developed to describe the relative motion in the Low Earth Orbit environment, considering both the unperturbed and the J2 and drag contributions. A Proportional, Integral and Derivative controller is implemented for the position control of a multiple satellite formation flying, considering a low thrust control profile. The Formation Flying L-band Aperture Synthesis study is taken as the case scenario, analysing both nominal and non-nominal configurations. This study serves as a starting point for the development of a combined tool to assess the performance of the interferometry and the control on the relative state for future remote sensing studies involving relative motion.

Leveraging Large‐scale CSF Proteomics to identify Disease Progression Biomarkers in Autosomal Dominant Frontotemporal Lobar Degeneration

AbstractBackgroundThe pathophysiological mechanisms driving frontotemporal lobar degeneration (FTLD) disease progression and corresponding biomarkers that capture these changes are not fully understood. We leveraged high‐throughput proteomics to identify networks of co‐expressed CSF proteins and candidate biomarkers for prediction of disease progression in adults with autosomal dominant FTLD mutations.Method113 adults carrying autosomal dominant FTLD mutations (C9orf72/GRN/MAPT) and 38 noncarrier controls from the ALLFTD consortium completed baseline lumbar puncture and longitudinal neuropsychological testing. CSF was assayed for SOMAmer proteomics on SOMAscan® v3.0 (4,140 proteins). Network analysis identified weighted protein co‐expression modules, which were annotated via gene ontology and cell‐type enrichment analysis. Disease age estimates that capture proximity to symptom onset were derived from a Bayesian disease progression model incorporating genotype‐specific clinical (cognition, CDR®+NACC FTLD) and biomarker (brain volume, plasma NfL) information. At baseline, local‐weighted regression examined module z‐scores (based on mean/SD of module levels [first principal component] in noncarriers) in relation to disease age. Longitudinal linear mixed‐effects models examined global cognitive trajectories in relation to baseline module z‐scores, as well as individual proteins within prognostic modules.ResultNetwork analysis identified 32 CSF protein co‐expression modules (37 to 223 proteins/module). 16 modules showed mutation‐related deviations from noncarriers. Deviations in ion transport, neurodevelopmental, metabolic, and transcriptional modules occurred several decades before estimated symptom onset (disease age: ‐30 to ‐20 years) and persisted across disease age. Deviations in neuroinflammatory and ubiquitination/autophagy modules occurred ∼10 years before estimated symptom onset. Sharp deviations in RNA binding, protein phosphorylation, neurogenesis, synaptic function, and lysosomal modules occurred near symptom onset (disease age: ‐1 to 4 years). Baseline synaptic and neurogenesis modules were the strongest prognosticators of cognitive decline (module x time: bs>.10, ps<.05). Within these modules, individual proteins with stronger intramodular connectivity exhibited stronger associations with cognitive decline (e.g., synaptic/transmembrane module: r = .40, p = 2.85e‐6; e.g., EPHA5, LRRTM2).ConclusionLarge‐scale analysis of the CSF proteome reveals a biologically‐diverse landscape of protein networks associated with presymptomatic and symptomatic stages of autosomal dominant FTLD. Synaptic and neuron‐enriched protein networks exhibited prodromal deviations that forecasted incipient cognitive decline. ‘Hub’ proteins derived from these affected networks warrant further validation as candidate biomarkers for early FTLD disease progression.

Leon Trotsky and the political conundrum of international relations

In this article we identify the ways in which Leon Trotsky’s ideas constitute a powerful resource to understand the contemporary crisis of international relations and its historical roots in the 20th century. Trotsky’s concept of uneven and combined development has already been highlighted as a signal contribution by an established scholarship in and around the discipline of International Relations. While this is a welcome development, we contend that it has come at a significant cost, detaching Trotsky’s theoretical insights from his revolutionary politics. We employ a different mode of engagement with Trotsky’s ideas, focusing on the theory of Permanent Revolution as an expression of an original analysis of the dialectic between the national and the international. Far from being a theoretically detachable and politically erroneous appendage to the more fundamental and applicable concept of uneven and combined development, we argue that Permanent Revolution constitutes its necessary culmination, as well as Trotsky’s most significant contribution to classical Marxism. We then elucidate how, writing in the first half of the 20th century and applying his theory of Permanent Revolution, Trotsky was able to diagnose certain essential lines of political development – the rise and ongoing breakdown of American hegemony, the political degeneration and collapse of the Soviet Union, and the emergence and failure of the postcolonial independent nation states – tracing the long and crisis-ridden trajectory of international relations from the second half of the 20th century down to today.

A novel trajectory similarity measurement method based on node‐sequence hierarchical digraph

AbstractTrajectory similarity measurement is a basic and vital task in trajectory data mining, which has attracted extensive research in the past decades. Recent works focused on the sequence and hierarchy property of trajectories to construct similarity measurements. However, these methods ignore the user information on the visiting locations, such as semantic and time distribution. In light of this, a novel trajectory similarity measurement based on Node‐Sequence Hierarchical Digraph (NSHD) framework is proposed in this article. We first propose a Time‐Weighted Stay Point Detection (TWSPD) method to extract real visiting locations of users more accurately. Then, the nodes of digraph are obtained by clustering users' stay points and the edges of digraph are sequence information that users move between these nodes. An Advanced Earth Mover's Distance (AEMD) is proposed to measure the node similarity between users, considering visiting time distribution and semantic information simultaneously. Both node and sequence similarities are used to calculate the similarity score to obtain the final trajectory similarity measurement. Experiments on Geolife and T‐Drive datasets show that our proposed method offers competitive performance with mean reciprocal rank values reaching 96.01 and 81.26%, which outperforms related trajectory similarity measurements by more than 10 and 15%.

A repository of COVID-19 related molecular dynamics simulations and utilisation in the context of nsp10-nsp16 antivirals

The coronavirus disease 2019 (COVID-19) pandemic highlighted the importance of establishing systems and infrastructure to develop vaccines, antiviral drugs, and therapeutic antibodies against emerging pathogens. Typical drug discovery processes involve targeting suitable proteins to effect pathogen replication or to attenuate host responses, by examining either large chemical databases or protein-protein interactions. Following initial screens, molecular dynamics (MD) simulations are critical for gaining further insight into molecular interactions. During the COVID-19 pandemic, many research groups made their simulations widely available, as highlighted by the comprehensive D.E. Shaw Research trajectory database. To investigate protein target sites and evaluate potential lead compounds, we performed over 300 MD simulations relating to COVID-19. We organised our simulations into a repository, which is publicly available at https://epimedlab.org/trajectories/. The trajectories cover a large part of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteome, and the majority of our MD simulations focused on the identification of potential antivirals. For example, we focused on the S-adenosyl-l-methionine binding site of the nsp10-nsp16 complex, a critical component of viral replication, revealing verbascoside as a potential lead. Moreover, we utilised MD trajectories to explore the interface between the spike protein receptor binding domain and human angiotensin-converting enzyme 2 receptor, with the ultimate aim being investigation of new variants in real-time. Overall, MD simulations are a critical component of the in silico drug discovery process and as highlighted throughout the pandemic, data sharing enables accelerated progress. We have organised our extensive collection of COVID-19 related MD trajectories into an easily accessible repository.

69 Influence of Cardiovascular Risk Factors on Neuropsychological Trajectories in Black/African American Adults Living with HIV

Objective:Human immunodeficiency virus (HIV) type 1 (HIV-1), cardiovascular disease, and HIV-associated neurocognitive disorders (HAND) disproportionately affect Black/African American individuals compared to other racial and ethnic groups. Understanding the mechanisms of cognitive health disparities is essential for developing policy and health interventions to combat such disparities. Cardiovascular risk factors/diseases are common comorbidities that likely contribute to cognitive health disparities among Black/African American people living with HIV (PWH), but their impacts on cognition longitudinally in this population are unclear. The current study examines the relationship between cardiovascular risk and cognitive functioning over time in Black/African American adults living with HIV.Participants and Methods:A sample of 122 Black/African American adults with HIV (ages 25-68, M=51.8, SD=7.7; 98% on antiretroviral therapy; 91% with undetectable viral load) were selected from the Drexel/Temple Comprehensive NeuroHIV Center, Clinical and Translational Research Support Core (CTRSC; based at Drexel University College of Medicine) Cohort. They completed longitudinal visits (300 total visits, average follow-up time=4.9 years) that included clinical interviews, medical record review, biometric measurements, and comprehensive neuropsychological assessments. Cardiovascular risk factors of interest were body mass index (BMI), waist-to-height ratio (WHtR), and a total vascular risk burden score (VBS) representing five risk factors: obesity, central obesity, diabetes, hyperlipidemia, and hypertension. Based on a prior principal component analysis, three cognitive domains were examined: (1) verbal fluency, (2) visual memory/visuoconstruction, and (3) motor speed/executive functions. Mixed models were used to examine domain-specific cognitive trajectories in relation to baseline cardiovascular risk factors and changes in cardiovascular risk factors.Results:Overall, cognitive test performance improved over time (p<.003). Baseline VBS was marginally associated with longitudinal change in verbal fluency (p=.06). Participants with low baseline VBS (0-1 risk factors) demonstrated improvement in verbal fluency (p=.002), while those with higher VBS (2-5 risk factors) demonstrated stability in verbal fluency. In contrast, greater increases in BMI and in WHtR predicted more favorable trajectories in motor speed/executive function (both p<.001). Patients with increasing BMI over time improved in this domain (p=.02), while patients with stable or decreasing BMI did not. A similar pattern was observed for WHtR change. No vascular risk factors were associated with trajectories of visual memory/visuoconstruction.Conclusions:Higher total vascular risk burden was associated with less favorable verbal fluency trajectories, reflecting the negative cognitive consequences of disorders such as diabetes, hyperlipidemia, and hypertension. Unexpectedly, greater increases in BMI and WHtR were associated with more favorable trajectories in motor speed and executive functioning. In this population, weight gain may be a proxy for other positive health factors, such as immune reconstitution, which will be examined in future analyses. Taken together, cardiovascular risk factors have heterogeneous associations with cognitive trajectories, emphasizing the importance of examining the mechanisms of these varying relationships. Future research will examine how social determinants of health, such as racial/ethnic discrimination, contribute to disparities in cardiovascular risk factors and cognitive outcomes.

Automated Method for SLAM Evaluation in GNSS-Denied Areas

The automated inspection and mapping of engineering structures are mainly based on photogrammetry and laser scanning. Mobile robotic platforms like unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs), but also handheld platforms, allow efficient automated mapping. Engineering structures like bridges shadow global navigation satellite system (GNSS), which complicates precise localization. Simultaneous localization and mapping (SLAM) algorithms offer a sufficient solution, since they do not require GNSS. However, testing and comparing SLAM algorithms in GNSS-denied areas is difficult due to missing ground truth data. This work presents an approach to measuring the performance of SLAM in indoor and outdoor GNSS-denied areas using a terrestrial scanner Leica RTC360 and a tachymeter to acquire point cloud and trajectory information. The proposed method is independent of time synchronization between robot and tachymeter and also works on sparse SLAM point clouds. For the evaluation of the proposed method, three LiDAR-based SLAM algorithms called KISS-ICP, SC-LIO-SAM, and MA-LIO are tested using a UGV equipped with two light detection and ranging (LiDAR) sensors and an inertial measurement unit (IMU). KISS-ICP is based solely on a single LiDAR scanner and SC-LIO-SAM also uses an IMU. MA-LIO, which allows multiple (different) LiDAR sensors, is tested on a horizontal and vertical one and an IMU. Time synchronization between the tachymeter and SLAM data during post-processing allows calculating the root mean square (RMS) absolute trajectory error, mean relative trajectory error, and the mean point cloud to reference point cloud distance. It shows that the proposed method is an efficient approach to measure the performance of SLAM in GNSS-denied areas. Additionally, the method shows the superior performance of MA-LIO in four of six test tracks with 5 to 7 cm RMS trajectory error, followed by SC-LIO-SAM and KISS-ICP in last place. SC-LIO-SAM reaches the lowest point cloud to reference point cloud distance in four of six test tracks, with 4 to 12 cm.

Inventory analysis of fire effects wrought by wind-driven megafires in relation to weather and pre-fire forest structure in the western Cascades

BackgroundSix synchronous, wind-driven, high severity megafires burned over 300,000 hectares of mesic temperate forest in the western Cascades of NW Oregon and SW Washington states in early September 2020. While remote sensing data has been utilized to estimate fire severity across the fires, assessments of fire impacts informed by field observations are missing. We compiled field measurement data, pre- and post-fire, from a statistically representative sample of existing forest inventory analysis (FIA) plots, to estimate stand-level fire effects indices that describe (1) tree survival and its implications for carbon emissions, (2) effects on tree crowns, and (3) effects on soils. Field observations were analyzed in relation to fire weather when plots burned and to evaluate accuracy of remotely sensed burn severity classifications.ResultsWind speed strongly interacted with tree size and stand age to influence tree survival. Under high fuel aridity but light winds, young stands composed of small trees, found primarily on private lands, exhibited a much lower survival rate than older stands composed of medium to large trees, found primarily on federal lands. Under moderate to high winds, poor tree survival was characteristic of all forest structures and ownerships. Fire impacts on tree crowns were strongly related to wind speed, while fire impacts on soils were not. These fires transferred nearly 70 MMT CO2e from wood in live and growing trees to a combination of immediate smoke and carbon emissions, plus delayed emissions from dead wood, that will release most of the embodied carbon over the next few decades. These emissions will exceed all 2020 anthropogenic emissions in Oregon (64 MMT CO2e). Substantial discrepancies were observed between two remotely sensed burn severity products, BAER-SBS and MTBS-TC, and field observed soil organic matter cover and tree mortality, respectively.ConclusionsPost-fire FIA plot remeasurements are valuable for understanding fire’s impact on forest ecosystems and as an empirical basis for model validation and hypothesis testing. This continuous forest inventory system will compound the value of these post-fire remeasurements, enabling analysis of post-fire forest ecosystem trajectories in relation to both immediate fire impacts and pre-fire conditions.

Agency amongst the entrepôts: Negotiating exchange associations between Motu hiri and Mailu seafaring exchange networks at Hood Bay on Papua New Guinea’s south coast

The exchange of specialized items and the social connections those exchanges engender play a fundamental role in the trajectories of societal relations. Processual archaeologists developed a core–periphery model to understand how these exchange relations work. The model evoked complex societal “cores” and “peripheries” at societal edges where exchanges with other cultures take place. The rigidity of core–periphery modeling led to the emergence of more nuanced network analyses to explain the qualitative as well as quantitative dimensions of cultural exchange. Yet contemporary models still focus on the agency of societal cores as central places. The agency and experiences of communities negotiating connections between exchange networks have gained little attention. In this study, we address this knowledge gap by exploring how the people of Hood Bay on Papua New Guinea’s south coast negotiated their position between the famed Motu hiri and Mailu seafaring exchange networks. Drawing on archaeological, ethnographic, and historical data, we examine how Hood Bay communities maintained and altered dynamic regional exchange associations through time. By highlighting the agency of communities living between exchange networks, this study contributes to understandings of the complex negotiation and organizing of exchange relations between cultures.

A proposed classification system for presigmoid approaches: a scoping review.

The "presigmoid corridor" covers a spectrum of approaches using the petrous temporal bone either as a target in treating intracanalicular lesions or as a route to access the internal auditory canal (IAC), jugular foramen, or brainstem. Complex presigmoid approaches have been continuously developed and refined over the years, leading to great heterogeneity in their definitions and descriptions. Owing to the common use of the presigmoid corridor in lateral skull base surgery, a simple anatomy-based and self-explanatory classification is needed to delineate the operative perspective of the different variants of the presigmoid route. Herein, the authors conducted a scoping review of the literature with the aim of proposing a classification system for presigmoid approaches. The PubMed, EMBASE, Scopus, and Web of Science databases were searched from inception to December 9, 2022, following the PRISMA Extension for Scoping Reviews guidelines to include clinical studies reporting the use of "stand-alone" presigmoid approaches. Findings were summarized based on the anatomical corridor, trajectory, and target lesions to classify the different variants of the presigmoid approach. Ninety-nine clinical studies were included for analysis, and the most common target lesions were vestibular schwannomas (60/99, 60.6%) and petroclival meningiomas (12/99, 12.1%). All approaches had a common entry pathway (i.e., mastoidectomy) but were differentiated into two main categories based on their relationship to the labyrinth: translabyrinthine or anterior corridor (80/99, 80.8%) and retrolabyrinthine or posterior corridor (20/99, 20.2%). The anterior corridor comprised 5 variations based on the extent of bone resection: 1) partial translabyrinthine (5/99, 5.1%), 2) transcrusal (2/99, 2.0%), 3) translabyrinthine proper (61/99, 61.6%), 4) transotic (5/99, 5.1%), and 5) transcochlear (17/99, 17.2%). The posterior corridor consisted of 4 variations based on the target area and trajectory in relation to the IAC: 6) retrolabyrinthine inframeatal (6/99, 6.1%), 7) retrolabyrinthine transmeatal (19/99, 19.2%), 8) retrolabyrinthine suprameatal (1/99, 1.0%), and 9) retrolabyrinthine trans-Trautman's triangle (2/99, 2.0%). Presigmoid approaches are becoming increasingly complex with the expansion of minimally invasive techniques. Descriptions of these approaches using the existing nomenclature can be imprecise or confusing. Therefore, the authors propose a comprehensive classification based on the operative anatomy that unequivocally describes presigmoid approaches simply, precisely, and efficiently.

Immigration Clashes, Party Polarization, and Republican Radicalization: Tracking Shifts in State and National Party Platforms since 1980

Abstract Studies of U.S. politics increasingly aim to make sense of two key trends: party polarization and Republican Party radicalization. Surprisingly, however, party divergences on immigration have been largely overlooked. Drawing on state and national political party platforms since 1980, we document the rise of attention to immigration, the polarization of substantive party positions, and the sharp GOP turn toward restrictive measures. After pinpointing the timing and relative trajectories of national and state-level agenda shifts, we explore potential drivers and establish two sets of flashpoint events worth further study: highly visible and mostly deadlocked congressional battles over immigration grand bargains, and bottom-up reverberations from the widespread 2006 immigrant rights protests and post-2008 Tea Party organizing. We find that grassroots Tea Party efforts were intervening accelerators rather than original causes of the Republican embrace of tough immigration restrictions. The article concludes by stressing the chronological layering of successive party polarizations—from 1960s divergences around civil rights, through clashes about abortion and LGBTQ rights from the late 1970s to the 1990s, and followed by immigration polarization in the 2000s. This process of layering polarizations on top of one another may have supercharged recent GOP turns toward ethnonationalism and tolerance for threats of violence.

Decentralized Differential Aerodynamic Control of Microsatellites Formation with Sunlight Reflectors

The paper presents a study of decentralized control for a satellite formation flying mission that uses differential lift and drag to enforce the relative positioning requirements. All spacecraft are equipped with large sunlight reflectors so that, given the appropriate lighting conditions, the formation as a whole can be made visible from the Earth as a configurable pixel image in the sky. The paper analyzes the possibility of achieving a pre-defined lineup of the formation by implementing decentralized aerodynamic-based control through the orientation of sunlight reflectors relative to the incoming airflow. The required relative trajectories are so-called projected circular orbits which ensure the rotation of the image with the orbital period. The choice of the reference trajectory for each satellite is obtained by minimizing the total sum of relative trajectory residuals. The control law is based on the linear-quadratic regulator with the decentralized objective function of reducing the mean deviation of each satellite’s trajectory relative to the other satellites. The accuracy of the required image construction and convergence time depending on the initial conditions and orbit altitude are studied in the paper.

Longitudinal Glycemic Trajectories in Relation to Toxic and Essential Metals among Mexican Americans

Longitudinal Glycemic Trajectories in Relation to Toxic and Essential Metals among Mexican Americans

OTE-SLAM: An Object Tracking Enhanced Visual SLAM System for Dynamic Environments.

With the rapid development of autonomous driving and robotics applications in recent years, visual Simultaneous Localization and Mapping (SLAM) has become a hot research topic. The majority of visual SLAM systems relies on the assumption of scene rigidity, which may not always hold true in real applications. In dynamic environments, SLAM systems, without accounting for dynamic objects, will easily fail to estimate the camera pose. Some existing methods attempt to address this issue by simply excluding the dynamic features lying in moving objects. But this may lead to a shortage of features for tracking. To tackle this problem, we propose OTE-SLAM, an object tracking enhanced visual SLAM system, which not only tracks the camera motion, but also tracks the movement of dynamic objects. Furthermore, we perform joint optimization of both the camera pose and object 3D position, enabling a mutual benefit between visual SLAM and object tracking. The results of experiences demonstrate that the proposed approach improves the accuracy of the SLAM system in challenging dynamic environments. The improvements include a maximum reduction in both absolute trajectory error and relative trajectory error by 22% and 33%, respectively.

Automated Fiber Placement Path Planning and Analysis of Pressure Vessels.

The automated fiber placement (AFP) process faces a crucial challenge: the emergence of out-of-plane buckling in thermoplastic prepreg tows during steering, significantly impeding the quality of composite layup. In response, this study introduces a novel approach: the development of equations for wrinkle-free fiber placement within composite pressure vessels. The investigation encompasses a detailed analysis of prepreg trajectories in relation to shell geometry, accompanied by an in-depth understanding of the underlying causes of wrinkling on dome surfaces. Moreover, a comprehensive model for shell coverage, grounded in placement parameters, is meticulously established. To validate the approach, a simulation tool is devised to calculate press roller motions, ensuring the uniform fiber dispersion on the mandrel and achieving flawless coverage of the shell without wrinkles. This innovative strategy not only optimizes the AFP process for composite layup but also remarkably enhances the overall quality of composite shells. As such, this research carries significant implications for the advancement of composite manufacturing techniques and the concurrent improvement in material performance.

Corporate‐startup partnering: Exploring attention dynamics and relational outcomes in asymmetric settings

AbstractResearch SummaryStartups that partner concurrently with a large corporation must compete for the latter's attention. We extend the attention‐based view from an intraorganizational to an interorganizational context, exploring how startups differ in the amount of attention they receive, their actions to attract and sustain attention, and the impact of attention dynamics on the relational outcome of the partnership. Our research uncovers two separate contests for attention involving corporate and divisional managers, highlighting the distributed nature of attention. Reflecting these, our findings reveal how startups' responsiveness to the respective cognitive schemas and corresponding stimuli of corporate and divisional managers is critical to understanding their distinct relational trajectories and disparate outcomes. Our focus on attention is complementary to the focus on trust that has hitherto dominated research on relational dynamics.Managerial SummaryStartups partner with large corporations to access needed complementary resources. However, truly benefiting from such partnerships is challenging and requires them to attract as well as sustain the latter's attention. Our study reveals two contests for attention: one with corporate managers tasked with running a startup partnering initiative and the other with divisional managers in business units with whom actual commercial joint activity is forged. These two sets of managers have different priorities (schemas) that result in differences in the nature and amount of attention they pay to startups' actions (stimuli). Startups seeking corporate partnerships would do well to recognize this heterogeneity within large corporations and accordingly manage the attention–attraction process through suitable partner‐centric behaviors. On their part, large corporations need to be aware of and sensitive to the challenges such disparate schema of corporate and divisional managers pose for successful partnering outcomes as the relationship transitions from the early to later stages.

Coordination control of the automated fiber placement system using photogrammetry-based leader–follower approach

The use of multiple robots in an automated fiber placement system (AFPS) makes it possible to manufacture composite structures with complex shapes. The robots in such system usually adopt independent trajectory planning and control methods. This makes the AFPS lack coordination, and rely heavily on the high-precision calibration of the system when completing complex fiber placement tasks. In this article, a novel photogrammetry-based leader–follower (PBLF) approach is proposed for a particular AFPS which consists of a serial manipulator and a parallel robot to improve its accuracy and coordination. The approach is composed of an offline trajectory planning module, a leader module, and a follower module. The trajectory planning algorithm in the offline trajectory planning module solves the problem of robot workspace constraints and mandrel occlusion in the fiber placement tasks for complex structure. Besides, a novel photogrammetry-based pose tracking method is proposed to make the follower robot track its desired relative trajectory with respect to the moving reference frame and keep the coordination of the two robots. The theoretical stability of the proposed approach is proved. The results of experiments indicate that the proposed approach can reduce the average mean absolute errors of the relative pose in position and orientation direction by 62.15% and 46.42%, respectively. While the corresponding average root mean square errors are reduced by 61.20% and 45.26%, respectively. Therefore, compared with Non-Coordination approach, the PBLF approach can effectively improve the coordination of the two robots.