Violent Movements Research Articles

Novel methods for reliability study of multi-dimensional non-linear dynamic systems

This research presents two unique techniques for engineering system reliability analysis of multi-dimensional non-linear dynamic structures. First, the structural reliability technique works best for multi-dimensional structural responses that have been either numerically simulated or measured over a long enough length to produce an ergodic time series. Second, a novel extreme value prediction method that can be used in various engineering applications is proposed. In contrast to those currently used in engineering reliability methodologies, the novel method is easy to use, and even a limited amount of data can still be used to obtain robust system failure estimates. As demonstrated in this work, proposed methods also provide accurate confidence bands for system failure levels in the case of real-life measured structural response. Additionally, traditional reliability approaches that deal with time series do not have the benefit of being able to handle a system's high dimensionality and cross-correlation across several dimensions readily. Container ship that experiences significant deck panel pressures and high roll angles when travelling in bad weather was selected as the example for this study. The main concern for ship transportation is the potential loss of cargo owing to violent movements. Simulating such a situation is difficult since waves and ship motions are non-stationary and complicatedly non-linear. Extreme movements greatly enhance the role of nonlinearities, activating effects of second and higher order. Furthermore, laboratory testing may also be called into doubt due to the scale and the choice of the sea state. Therefore, data collected from actual ships during difficult weather journeys offer a unique perspective on the statistics of ship movements. This work aims to benchmark state-of-the-art methods, making it possible to extract necessary information about the extreme response from available on-board measured time histories. Both suggested methods can be used in combination, making them attractive and ready to use for engineers. Methods proposed in this paper open up possibilities to predict simply yet efficiently system failure probability for non-linear multi-dimensional dynamic structure.

Isolated Dystonia as an Initial Presentation of GDAP2-Related Disorder.

Isolated Dystonia as an Initial Presentation of GDAP2-Related Disorder.

Real-Time 3D Reconstruction of Large-Scale Scenes with LOD Representation

Real-time 3D reconstruction of static scenes can be achieved based on the RGB-D image sequence fusion. It is a popular practice to divide the space into uniform voxels and use a truncated signed distance function to represent surface information. In order to represent a scene of large scale, the voxel hash algorithm which stores voxels compressively can be used, but most of the conventional methods do not consider the complexity and roughness of the object surface in the scene, so the scene is represented with a uniform resolution. It somewhat limits the range of scene representation and the speed of real-time reconstruction. In this paper, a large-scale scene reconstruction algorithm based on voxel hashing storage with LOD representation is proposed. The main contributions include the following two aspects: (1) By preprocessing the depth image with smooth filtering, which ensures the accuracy of the data, it can effectively reduce the distortion caused by the sensor itself and violent motion and provide better support for the stages of voxel hashing, model rendering, and frame-to-model camera position tracking. (2) The 3D reconstruction with LOD representation is realized. We take the view distance and the roughness of the model surface as criteria to control the adaptive division and representation of spatial voxel blocks. Finally, we carried out qualitative and quantitative evaluations of the algorithm, and confirmed that the algorithm can achieve real-time reconstruction with different levels of detail in the commercial graphics processing hardware environment, and achieve a good fusion effect in large-scale scenes.

Understanding Social Phenomena Linked to Religion: In Search of an Alternative Approach That Combines Science with Religious Insights

Some contemporary social phenomena, despite secularization, are still linked to religion. However, this same secularization seems to have accompanied a progressive process of religious illiteracy. Therefore, the capacity to address religious inspired issues is lower than the magnitude of the problems at work, be violent right-wing movement and Islamist terrorism or ethical debates on the beginning and end of life, to name but a few. Hence, this paper aims to fulfil three goals: to revisit secularism and some liberal assumptions that might prevent a correct understanding of these phenomena, to assess some of the consequences of the critique of ideologies and to propose an alternative approach to address religious inspired social phenomena.

WHU-Helmet: A Helmet-Based Multisensor SLAM Dataset for the Evaluation of Real-Time 3-D Mapping in Large-Scale GNSS-Denied Environments

Real-time 3D mapping of large-scale Global Navigation Satellite System (GNSS)-denied environments plays an important role in forest inventory management, disaster emergency response, and underground facility maintenance. Compact helmet laser scanning (HLS) systems keep the same direction as the user’s line of sight and have the advantage of “what you see is what you get”, providing a promising and efficient solution for 3D geospatial information acquisition. However, the violent motion of the helmet, the limited field of view of the laser scanner, and the repeated symmetrical geometric structures in GNSS-denied environments pose enormous challenges for the existing simultaneous localization and mapping (SLAM) algorithms. To promote the development of HLS and explore its application in large-scale GNSS-denied environments, the first large-scale HLS dataset covering multiple difficult GNSS-denied areas (e.g., forests, mountains, underground spaces) was built in this study. Besides using an additional very high accuracy fiber-optic inertial measurement unit (IMU), a novel post-processing multi-source fusion method—progressive trajectory correction (PTC)—is proposed to generate a reliable ground-truth trajectory for the benchmark, which overcomes the problems of scan matching degradation and non-rigid distortion. The accuracies of the ground truth are controlled and checked by manually surveyed feature points along the trajectory. Finally, the existing state-of-the-art SLAM methods were evaluated on the WHU-Helmet dataset, summarizing the future HLS SLAM research trends. The full dataset is available for download at: https: //github.com/kafeiyin00/WHU-HelmetDataset.

Temperatures leading to heat escape responses in Antarctic marine ectotherms match acute thermal limits.

Thermal tolerance windows are key indicators of the range of temperatures tolerated by animals and therefore, a measure of resilience to climate change. In the ocean, where ectotherms are immersed, body temperatures are tightly coupled to environmental temperature and species have few options for thermoregulation. However, mobile species do have the ability to orientate towards optimal temperatures and move away from sub-optimal or dangerous temperatures. Escape responses are one such locomotory behavior, which typically manifests as a series of violent flicking movements that move individuals out of dangerous environments. We tested 11 species of Antarctic marine ectotherms, from one of the most stable shallow water marine environments, with an annual temperature range of -2°C to +2°C, that are vulnerable to small degrees of warming. Three species, the clam Laternula elliptica, the sea cucumber Cucumaria georgiana, and the brittlestar Ophionotus victoriae, showed no, or virtually no, escape response to temperature. Escape responses from a further eight species had a median response temperature of 11.2 (interquartile range, 10°C-15.7°C), which is well above current environmental temperatures but close to the range for acute lethal limits of Antarctic marine ectotherms (CTmax range, 17.2°C-26.6°C). This highlights that both acute tolerance limits and escape responses, fall outside current environmental temperatures, but also those predicted for 100s of years in the Southern Ocean. In a warmer Southern Ocean Antarctic fauna may not have the capacity to use temperature to select optimal thermal conditions, which leaves adaptation as a primary mechanism for their persistence.

Artificial intelligence-based approach for cluster identification in a CFB riser

Cluster evolution dominates the gas–solid interaction and heat and mass transfer in risers, but cluster identification is still a challenge. Based on the unsupervised artificial intelligence approach, a two-step K-means cluster identification method is proposed to distinguish the clusters in a riser. With the consideration of the instantaneous particle motion and position information, it is able to capture the phenomenon of particles attaching and detaching a cluster. The estimated solid fraction threshold is located in the region where the slope of the solid fraction is the smallest, and approximately makes the numbers of particles detaching and attaching the clusters equal. The solid fraction threshold is about 0.204. It is found that the particles penetrating a cluster are in a more violent turbulent movement. Larger gas velocity and solid flux result in stronger interactions between clusters. The proposed method provides a new way to identify the cluster.

Cargo ship aft panel stresses prediction by deconvolution

This article introduces novel extreme value prediction method that can be used for a variety of offshore engineering applications. First, to demonstrate the novel method, fictitious data from a non-linear Duffing oscillator and measured wave heights were used as examples. The second incident included a container ship that experienced significant deck panel strains while traveling across the Atlantic Ocean in bad weather. The main concern for cargo ship transportation is potential loss of container owing to violent movements. It is challenging to model such a situation because waves and ship motions are both non-stationary and complicatedly nonlinear. Extreme motions greatly increase the role of nonlinearities, activating effects of second and higher order.Furthermore, due to the scaling and the choice of sea state, laboratory testing may also be called into doubt. Therefore, data collected from actual ships during difficult weather voyages offers a special perspective on the statistics of ship motions.This paper aims to highlight an alternative method of extrapolation that is based on intrinsic properties of the data set itself and does not assume any extrapolation functional class. Extreme value predictions typically originate from certain statistical distribution functional classes to fit the data and then extrapolate. Engineering design can make use of the unique extrapolation method that has been proposed. The proposed method's forecast accuracy has been verified in comparison to the Averaged Conditional Exceedance Rate (ACER) extrapolation method.

Theoretical Analysis of the Movement Law of Top Coal and Overburden in a Fully Mechanized Top-Coal Caving Face with a Large Mining Height

In recent years, with the rapid development of equipment manufacturing and advances in the research on mine pressure and rock mechanics, large-mining-height comprehensive mechanized coal mining technology has become increasingly widely used in thick-seam mining. On this basis, because the free space extracted is several times that of layered mining, the occurrence of strong ground pressure caused by the violent movement of the basic roof and the low recovery rate of the top coal have become the main problems. In this study, Dong Liang Coal Mine was taken as the engineering background by which to study the three typical movement forms of the basic roof, and the critical fracture conditions of the three forms were obtained through theoretical calculations. The movement result state of the basic roof strata was taken as the different overlying boundary conditions of the top coal to simulate its impact on the recovery rate, to explore the interaction mechanism between the basic roof strata and the top coal, and for use as a theoretical basis to guide engineering practice to improve energy recovery rates and safety efficiency.

Linear friction welding of Ti60 near-α titanium alloy: Investigating phase transformations and dynamic recrystallization mechanisms

Linear friction welding (LFW) is a solid-state welding process used primarily in manufacturing of aeroengine blisks. Ti60 near-α titanium alloy was developed for blisks operating at 600 °C, and shows excellent thermal stability and high-temperature oxidation resistance. In order to promote the wider use of such blisks, the mechanisms of microstructure evolution including phase transformation and dynamic recrystallization of welded Ti60 joint were studied. The effects of phase transformation and dynamic recrystallization on microhardness and tensile strength were investigated as well. Results show that the microstructure of the thermo-mechanically affected zone (TMAZ) deforms severely along the friction direction, forming {0001}[11 2 ¯ 0] α texture. β → metastable β then → α + β transformations occur, leading to lamellar α precipitating from the deformed β. Sufficient continuous dynamic recrystallization makes the WZ almost composed of fine equiaxed grains of 10 μm size. In addition, α → β with the subsequent αˊ transformation occurs in the weld zone (WZ), producing extensive distribution of acicular αˊmartensite inside the recrystallized grains. Under the effects of strain hardening, precipitation strengthening and fine grain strengthening, the hardness in WZ increases significantly (i.e., 381 HV) compared to base metal (BM) (335 HV), with the tensile strength of the joint (943 MPa) also increasing over that of the BM (914 MPa). However, because of inhomogeneous deformation, the elongation of the joint (13.3%) is slightly lower than that of BM (14.1%). • β → metastable β then → α + β transformations occur in TMAZ, leading to lamellar α precipitating from deformed β; α → β with the subsequent αˊ transformation occurs in WZ, producing extensive distribution of acicular αˊmartensite. • Adequate continuous dynamic recrystallization occurs in weld zone, accompanying by violent dislocation motion and formation of many subgrains and low-angle grain boundaries. • The tensile strength of the joint (943 MPa) increases to that of the base metal (914 MPa), but the elongation of the joint (13.3%) is slightly lower than that of the base metal (14.1%) because of inhomogeneous deformation.

STUDY OF VIOLENCE RECOGNITION FROM VIDEO BASED ON ARTIFICIAL INTELLIGENCE

This paper will discuss current approaches to the recognition of violent human actions. Recognition accuracy for these methods will also be presented. In the modern world due to development of sensory and visual technologies systems of recognition of violent actions of the person have become popular. The problem of aggression, including children's aggression, has long attracted the attention of psychologists. Among methods using violence there are several separate methods: methods of detection of violence using machine learning, methods of detection of violence using SVM and methods of detection of violence using deep learning. The purpose of this study is to review current software solutions for recognizing violent movements from video. During the work done, an analysis of existing machine learning and artificial intelligence algorithms for automatic detection of aggression was made. And also the application of the PoseNet method for aggression detection was tested and proposed. An attractive feature of the algorithm is that its performance is not affected by the number of people in the input image. Pose evaluation models take the processed camera image as input data and output information about the key points.

Trust in Elections

Abstract The sometimes violent movement to reject the outcome of the 2020 U.S. presidential election draws our attention to the topic of trust in the institution of American election administration. An examination of this topic must make an important distinction between trust in elections (a psychological construct) and the trustworthiness of election results (a legal construct). The history of election administration in the United States is full of examples of efforts to increase the trustworthiness of elections to ensure that results are based on fair and competent administration. The resilience of these efforts was on display following the 2020 election, as formal institutions rejected claims that the election was fraudulent. Still, the past two decades have seen a decline in trust in American elections that has primarily been driven by a slow but steady decline in trust among Republicans. Surprisingly, the increased polarization in trust most recently has been due more to Democrats suddenly becoming more trusting. Election officials must continue to try to overcome attacks on trust in the system, but it is unclear how long they can sustain the legal system guaranteeing free and fair elections without broad-based public trust in how we administer elections.

9/11 was an Instance of Transnational Balancing: An Intervention in Statist IR Theory

With the end of the Cold War and through the start of the 21st century, conventional IR theories were anticipating an eventual balancing against the United States. Puzzled when this phenomenon did not occur, balancing theorists engaged in a lively discussion, bringing with it the development of proposed alternative forms of balancing and a debate over whether the concept itself had perhaps outlived its relevance. This article reengages with this discussion, suggesting that many of the involved theorists were hampered by theoretical blinders based on statism, and that in fact balancing did occur, but in an unconventional manner and at the hands of an unexpected suspect: al Qaeda, a violent non-state actor, acting in a transnational manner. In this context, this article treats the 9/11 attacks of the violent Jihadist anti-Western movement as an instance of balancing against the hegemon, a successful one in that the Jihadists arguably aimed not at “winning,” but at revealing the superpower’s weaknesses so that others would subsequently join the balancing effort. By failing to view the Jihadists’ efforts as an ideological balancing effort, the United States responded with force rather than ideational counter-balancing. They waged a war instead of emphasizing efforts to separate the radical violent Jihadist perpetrators from the idea they were championing—a struggle in the name of Muslims/the downtrodden East against the United States—and thus allowing the challenger to rise into a position of "dissident" in the Muslim world, and, arguably, paving the path for today's state revisionist behaviors. The article proposes a framework based on traditionally state-based concepts of intent and impact/capacity to show how non-state actors can in fact balance superpowers and therefore should be incorporated into balancing theories, and presents the actions of the violent Jihadists as an example of transnational, ideational balancing—a phenomenon as real and consequential as state-balancing.

Damping Characteristics of Cantilever Beam with Obstacle Grid Particle Dampers

In order to understand the damping effect and energy dissipation mechanism of the obstacle grid particle dampers, we conduct experimental and simulated studies. In this paper, the obstacle grid particle dampers are applied to the cantilever beam structure. The effect of filling ratio, particle size, particle material and excitation amplitude of the obstacle grid particle damper on the vibration characteristics of the cantilever beam is studied experimentally and compared with the conventional particle damper for damping effect. A simulation model of the particle damper was developed and experimentally validated using the discrete element method. The experimental results show that the vibration acceleration response of the obstacle grid particle damper decreases by 10.4 dB compared with the conventional particle damper at 90% filling ratio. The obstacle grid particle damper increases the area of energy transfer between the external vibration energy and the particles. It makes the particles, which originally have almost no contribution to the energy dissipation, produce violent motion and participate in the energy dissipation process, thus effectively improving the damping performance of the particle dampers.

Updating nonviolent campaigns: Introducing NAVCO 2.1

In this article, we introduce an updated version of the Nonviolent and Violent Campaigns and Outcomes dataset (NAVCO 2.1), which compiles annual data on 389 nonviolent and violent mass movements for regime change, anti-occupation, and secession from 1945 to 2013. This version of the dataset corrects known coding errors in NAVCO 2.0, adds news cases (including the Arab uprisings), and codes attributes for each campaign year (such as participation size and diversity, the behavior of regime elites, repression and its effects, support from external actors, and campaign outcomes). In addition, NAVCO 2.1 adds several new attributes to each campaign-year, including more precise participation figures, more nuanced data about the scope, intensity, and degree of violent flank behavior and state repression, and further information about the parallel or alternative institutions developed by the campaign. The data reveal four key findings: (1) that the success rate of nonviolent resistance campaigns has declined since 2001; (2) that far more people have participated in nonviolent than violent campaigns in the postwar period; (3) that nonviolent campaigns suffer far fewer per-capita fatalities than armed campaigns; and (4) that incidental violence by dissidents has become a more common feature of contemporary nonviolent campaigns compared with earlier cases. The article concludes with suggestions for further research.

DGFlow-SLAM: A Novel Dynamic Environment RGB-D SLAM without Prior Semantic Knowledge Based on Grid Segmentation of Scene Flow.

Currently, using semantic segmentation networks to distinguish dynamic and static key points has become a mainstream designing method for semantic SLAM systems. However, the semantic SLAM systems must have prior semantic knowledge of relevant dynamic objects, and their processing speed is inversely proportional to the recognition accuracy. To simultaneously enhance the speed and accuracy for recognizing dynamic objects in different environments, a novel SLAM system without prior semantics called DGFlow-SLAM is proposed in this paper. A novel grid segmentation method is used in the system to segment the scene flow, and then an adaptive threshold method is used to roughly detect the dynamic objects. Based on this, a deep mean clustering segmentation method is applied to find potential dynamic targets. Finally, the results of grid segmentation and depth mean clustering segmentation are jointly used to find moving objects accurately, and all the feature points of the moving objects are removed on the premise of retaining the static part of the moving object. The experimental results show that on the dynamic sequence dataset of TUM RGB-D, compared with the DynaSLAM system with the highest accuracy for detecting moderate and violent motion and the DS-SLAM with the highest accuracy for detecting slight motion, DGflow-SLAM obtains similar accuracy results and improves the accuracy by 7.5%. In addition, DGflow-SLAM is 10 times and 1.27 times faster than DynaSLAM and DS-SLAM, respectively.

Waterproof conductive fiber with microcracked synergistic conductive layer for high-performance tunable wearable strain sensor

With the rapid development of wearable smart electronic devices, flexible strain sensors with high sensitivity in a wide working range are urgently demanded. Meanwhile, good self-cleaning and anti-corrosion properties are also essential for daily use. Herein, a waterproof conductive spandex fiber strain sensor with microcracked synergistic Ag nanoparticles (AgNPs)-carbon nanotubes CNTs conductive layer was designed and fabricated via the solvent swelling, non-solvent-induced phase separation (NIPS), and low surface energy treatment process. Benefiting from the stable synergistic conductive network and the ultrasensitive microcrack structure, the sensor exhibits excellent overall strain sensing performances, including high sensitivity (gauge factor is 48,310 within 335–400% strain), wide working range (0–400%), ultralow detection limit (0.1%), fast response/recovery time (80 ms/100 ms), and long-term fatigue resistance over 10,000 cycles, making it reliably and precisely distinguish both violent human movements and subtle physiological signals. More importantly, strain sensing range and sensitivity of the sensor can also be effectively tunned through changing the AgNPs loading in the synergistic conductive network, enabling it to be applicable for different application scenarios. What’s more, the waterproof surface with good self-cleaning and anti-corrosion properties also endows the sensor with great potential for real-time body motion monitoring under humid and underwater environments without being interfered. This study provides a facile one-step method for the fabrication high-performance flexible strain sensor.

Dynamic and Thermal Investigations of the Forward Dry-Friction Whirl/Whip of a Vertical Rotor-AMB System during Touchdowns

When an active magnetic bearing (AMB) rotor drops, it impacts the touchdown bearing (TDB) and produces friction on its surface. The vertical AMB rotor has no stable support in the radial direction, and the rotor exhibits a violent whirl motion in the gap of the TDB. In this study, a complete dynamic and thermal model of the AMB-rotor-TDB system was established, and the complete drop process was simulated. When the rotor dropped, it obtained stable support after several bounces on the thrust surface of the TDB inner ring in the axial direction. In the radial direction, the rotor entered whirl motion after the initial collisions. There is a natural whirl frequency so that the drop forward whirl is divided into the dry-friction whirl and whip states. The contact force and heat generation of the TDB were monitored in the simulation and had different performancs in the two states. Both the initial collisions and the stabilized whirl motions were studied to evaluate the reliability of the TDB. Finally, a series of drop tests were performed, and the experimental results were in good agreement with the simulation.

Coherent Intramolecular Excimer Formation in Solid [2,2]‐Paracyclophane: Time‐Resolved Springing of a Molecular “Trap”

AbstractImpulsive UV excitation unleashes violent wave packet motions in [2,2]‐paracyclophane (2PC) due to relief of ground state inter‐ring repulsion. Contrary to theoretical predictions for the benzene excimer, transient absorption spectroscopy in oriented single crystals and in liquid THF demonstrates that excited 2PC absorbs visible light polarized along all three molecular axes. Absorption polarized perpendicular to the aromatic rings is deeply modulated in time by the ∼0.5 Å of light induced inter‐ring breathing providing changes in potential energy gaps and dipole strengths during coherent intramolecular excimer formation. Overlapping transitions to several higher electronic states and strong non‐Condon effects contribute to the modulating spectra. These insights prove current understanding of the simplest archetypal organic excimer is fundamentally flawed and provide the basis for testing improved electronic structure models. It is hard to overestimate the significance of achieving such improved understanding given the impact of excimers and exciplexes on all aspects of organic molecular photophysics.

Simulating Slosh Induced Damping, with Application to Aircraft Wing-like Structures

The added damping generated by liquid sloshing in a tank has been utilized in a number of civil applications, including aviation, to reduce the vibration of the system. As part of a wider EU H2020 project called SLOWD (Sloshing Wing Dynamics), the presented study performed numerical simulations on the slosh-induced damping of liquid in tanks that were under free decay oscillations and embedded in an aircraft wing-like structure. A new open-source partitioned fluid–structure interaction software framework is presented and employed for the numerical simulations. Periodic sloshing waves and violent vertical fluid motions are observed in the study. These demonstrate the effects of slosh-induced damping under different excitation amplitudes of the structure and a varying number of baffled regions within the tank. Various sloshing patterns caused by different combinations of the excitation amplitude and compartment numbers lead to different induced dampings of the free decay motion. We observed a distinctly non-monotonic function on the slosh damping when the initial excitation amplitude is small (i.e., 0.25), with a 59% reduction when we increase the number of baffled compartments from one to four, and a 153% increase when moving from one to eight compartments. This is due to the change in the sloshing wave frequency, resulting in a significant change in the impact of the fluid between the tank ceiling and the wave crests. When the initial excitation amplitude is large (i.e., 1.0), there is no significant change in the slosh-induced damping when changing the number of compartments in the tank, for the range of parameters considered, due to the highly turbulent fluid motion. This work is expected to form the basis of further, more detailed studies within the context of the SLOWD project and its ever-expanding experimental data output.