Wide Bumps Research Articles

Analysis of car speed reduction due to concrete speed bumps on local roads in Surakarta city

Increasing the volume of cars passing through local roads in residential areas and the various dimensions of concrete speed bumps made by citizens for safety, makes it important to conduct research on the correlation of car speed and the variables that influence the presence of speed bumps. The variables used are speed variables, dimensions of concrete speed bumps and road shoulder width. The speed variable used is the speed of the car before crossing the speed bumps with the help of an artificial line on the video or vehicle recording results. From the analysis of car speed before passing concrete speed bumps, it was found that speed bumps can reduce speeds by 80.17%. The car speed reduction model is Y2 = 12,762-0181 X2 + 0.114X3. Y2 = speed at a distance of 16 meters before speed bumps, X2 has wide speed bumps (cm) and X3 is the average width of the shoulder (m), and R2 is 0.970. This model applies to the condition of the dimensions of the width of the speed bumps 32.6 - 57 cm and the shoulder width of the road 30 – 100 cm.

A Wearable Sensory Textile‐Based Clutch with High Blocking Force

A sensory textile‐based clutch (STBC) activated by vacuum is presented. The STBC is an assembly of two inextensible webbings equipped with 2.3 mm wide rigid bumps fabricated directly on them by a hot embossing technique, and two elastic bands, all air sealed by a silicone elastomer cover. While, in passive mode, the clutch provides low resistance to elongation, upon vacuum, the specular rigid bumps interlock and provide a high withstanding force. The embedded capacitive‐based transducer allows encoding the clutch's elongation, with a position resolution reaching 1.15 mm, owing to a real‐time processing algorithm. The STBC (140 mm × 30 mm × 8 mm) sustains up to 419 N force with an activation pressure of −0.5 atm. The small size of the rigid components and a priming strategy (keeping the pressure at −0.01 atm in disengaged mode) enable response times down to 14 ms for a 115 N blocking force. A preliminary demonstration of a fully worn device shows the potential of the STBC approach for enabling the control of the engagement and disengagement of blocking forces, as well as monitoring of typical parameters of human movement such as knee bending angles, for future developments of light and efficient unpowered exoskeletons.

On the merger rate of primordial black holes: effects of nearest neighbours distribution and clustering

One of the seemingly strongest constraints on the fraction of dark matter in the form of primordial black holes (PBH) of \U0001d4aa(10) M⊙ relies on the merger rate inferred from the binary BH merger events detected by LIGO/Virgo. The robustness of these bounds depends however on the accuracy with which the formation of PBH binaries in the early Universe can be described. We revisit the standard estimate of the merger rate, focusing on a couple of key ingredients: the spatial distribution of nearest neighbours and the initial clustering of PBHs associated to a given primordial power spectrum. Overall, we confirm the robustness of the results presented in the literature in the case of a narrow mass function (which constrain the PBH fraction of dark matter to be fPBH≲ 0.001–0.01). The initial clustering of PBHs might have an effect tightening the current constraint, but only for very broad mass functions, corresponding to wide bumps in the primordial power spectra extending at least over a couple of decades in k-space.

Running bumps from stealth bosons

For the ‘stealth bosons’ S, light boosted particles with a decay S rightarrow A A rightarrow q bar{q} q bar{q} into four quarks and reconstructed as a single fat jet, the groomed jet mass has a strong correlation with groomed jet substructure variables. Consequently, the jet mass distribution is strongly affected by the jet substructure selection cuts when applied on the groomed jet. We illustrate this fact by recasting a CMS search for low-mass dijet resonances and show a few representative examples. The mass distributions exhibit narrow and wide bumps at several locations in the 100–300 GeV range, between the masses of the daughter particles A and the parent particle S, depending on the jet substructure selection. This striking observation introduces several caveats when interpreting and comparing experimental results, for the case of non-standard signatures. The possibility that a single boosted particle decaying hadronically produces multiple bumps, at quite different jet masses, and depending on the event selection, brings the anomaly chasing game to the next level.

Profile of multiboson signals

We investigate the visibility of signals characterised by wide bumps over a smoothly falling background that cannot be accurately predicted by Monte Carlo calculations. Examples of such are the wide bumps that triboson and quadriboson resonance cascade decays would yield in diboson resonance searches in fully hadronic final states. We find that the sensitivity to triboson bumps is rather small: signals of a moderate size could be present in current data and yet remain unnoticed. For quadriboson cascade decays the signals can hardly be distinguished from the background in the current searches.

Susceptibility modelling of hummocky terrain distribution using the information value method (Deception Island, Antarctic Peninsula)

The hummocky terrains of Deception Island (Antarctic Peninsula) are continuous surfaces with decimetre to metre wide and decimetre depth bumps located mainly in the lower section of sloping lapilli and scoria terrains. A detailed study site between Cerro Caliente and Crater Lake was selected for the detailed mapping of hummocky terrains and for modelling their spatial distribution according to controlling geographical factors. A model of the susceptibility of occurrence of the hummocky terrains was created using the information value method, together with five independent variables: elevation, slope, global summer radiation, total curvature and lithology. Success and prediction rate curves were used for model validation and the Area Under the Curve index was used to quantify the levels of performance and prediction. The results were of high quality with a success rate of 88% and a prediction rate of 78%. The classes of the independent variables with more relevance in the occurrence of hummocky terrains were: elevation between 20–30m and 60–70m; concave or rectilinear/flat areas; slopes between 8 and 12º; tuff cones and maar deposits and global summer radiation between 1.8 and 2.0 TJm−2. The good quality of the modelling results supports its use for assessing the future potential for formation of new hummocky terrain areas, or even to estimate the spatial distribution of buried ice within the permafrost environment of Deception Island.

Theory of growth and mechanical properties of nanotubes

We have investigated the growth and mechanical properties of carbon nanotubes using a variety of complementary theoretical techniques. Ab initio molecular dynamics calculations show that the high electric field present at the tube tips in an arc-discharge apparatus is not the critical factor responsible for open-ended growth. We then show by explicit molecular dynamics simulations of nanotube growth that tubes wider than a critical diameter of 3 nm, that are initially open, can continue to grow straight and maintain an all-hexagonal structure. Narrower tubes readily nucleate curved, pentagonal structures that lead to tube closure with further addition of atoms. However, if a nanotube is forced to remain open by the presence of a metal cluster, defect-free growth can continue. For growth catalyzed by metal particles, nanometer-sized protrusions on the particle surface lead to the nucleation of very narrow tubes. Wide bumps lead to a strained graphene sheet and no nanotube growth. We have also simulated the growth and properties of double-walled nanotubes with the aim of investigating the role of lip-lip interactions on nanotube growth. Surprisingly, the lip-lip interaction by itself does not stabilize open-ended growth, but rather facilitates tube closure by mediating the transfer of atoms between inner and outer shells. Furthermore, a simulation of growth on a wide double-wall nanotube leads to considerable deviations from the ideal structure, in contrast to corresponding simulations for single-wall tubes that result in nearly perfect structures. As regards mechanical properties, carbon nanotubes, when subjected to large deformations, reversibly switch into different morphological patterns. Each shape change corresponds to an abrupt release of energy and a singularity in the stress-strain curve. The transformations, observed in molecular dynamics simulations, are explained well by a continuum shell model. With properly chosen parameters, the model provides a remarkably accurate roadmap' of nanotube behavior beyond Hooke's law. We have also investigated static and dynamical properties of carbon nanotubes under uniaxial tension by quantum and classical simulations. In strained nanotubes at high temperatures double pentagon-heptagon defect pairs are spontaneously formed. Their formation is energetically favorable at strains greater than 5%. They act as nucleation centers for the formation of dislocations in the originally ideal graphite network and lead to the onset of a plastic deformation of the carbon nanotube.

Kinetics of metal-catalyzed growth of single-walled carbon nanotubes

Molecular-dynamics and total-energy calculations using a realistic three-body potential for carbon reveal the basic atomic processes by which single-shelled nanotubes can grow out of metal-carbide particles by the root growth mechanism. We find that nanometer-sized protrusions on the metal-particle surface lead to the nucleation of very narrow tubes. Wide bumps lead to a strained graphene sheet and no nanotube growth. The results also explain the absence of multishelled tubes in metal-catalyzed growth.