Jamming Behavior Research Articles

Interplay between jamming and percolation upon random sequential adsorption of competing dimers and monomers

The competitive random coadsorption of dimers and monomers, with probabilities P(D) and P(M), such as P(D)+P(M)=1, respectively, is studied numerically by means of Monte Carlo simulations. Excluded volume and nearest-neighbor infinite repulsion between unlike species is considered. The subtle interplay between competitive coadsorption, jamming behavior and the emergency of percolation clusters is analyzed in detail. Taking P(M) as the single parameter of the model, five characteristic regions where the system exhibit different physical behavior can be identified: I) For P(M)< or =P(M1) approximately equal to 0.4025(25) the standard percolation of dimers is observed; II) Within the interval P(M1)<P(M)<P(*)(M1) approximately equal to 0.4375(25) clusters of all species (monomers, dimers, and empty sites) are finite (nonpercolating); III) For P(*)(M1)< or =P(M)< or =P(*)(M2) approximately equal to 0.5425(25) the percolation of homogeneous clusters of empty sites is observed; IV) Within the interval P(*)(M2)<P(M)<P(M2) approximately equal to 0.5575(25), the system behaves as in Region II; and finally, V) For P(M2)< or =P(M), one has the standard percolation of monomers.

Jamming and asymptotic behavior in competitive random parking of bidisperse cars

We propose a generalized car parking problem where either a car of size σ or of size mσ ( m>1) is sequentially parked on a line with probability q and (1− q), respectively. The free parameter q interpolates between the classical car parking problem at either extreme ( q=0 and 1) and the competitive random sequential adsorption of a binary mixture in between. We find that the coverage in the jamming limit for a mixture always exceeds the value obtained for the uni-sized case. The introduction of a bidisperse mixture results in the slow approach (∼ t −1) to the jamming limit by the smaller species while the larger species reach their asymptotic values exponentially fast ∼ t −1e −( m−1) qt .

Random walk theory of jamming in a cellular automaton model for traffic flow

The jamming behavior of a single lane traffic model based on a cellular automaton approach is studied. Our investigations concentrate on the so-called VDR model which is a simple generalization of the well-known Nagel–Schreckenberg model. In the VDR model one finds a separation between a free flow phase and jammed vehicles. This phase separation allows to use random walk like arguments to predict the resolving probabilities and lifetimes of jam clusters or disturbances. These predictions are in good agreement with the results of computer simulations and even become exact for a special case of the model. Our findings allow a deeper insight into the dynamics of wide jams occuring in the model.

The distribution of stress-drop sizes in serrated flow of an aluminium alloy and a mild steel

Serration and noise behaviors in plastically deforming solids are related to avalanches of deformation processes. In the stress-strain curves, the serration characteristics are visible as stress drops or strain jumps. In fact, similar serration characteristics are ubiquitous in many structural and functional materials, such as amorphous materials [also metallic glasses, or bulk metallic glasses (BMGs)], high-entropy alloys (HEAs), superalloys, ordered intermetallics, shape-memory alloys (SMAs), electrochemical noise, carbon steels, twinning-induced plasticity steels (TWIP steels), phase-transformation-induced plasticity steels (TRIP steels), Al-Mg alloys, nano-materials, magnetic functional materials, and so on. Because of their unique and universal properties, many researchers have focused on this field to find out what causes the serration behaviors and what can be learned about the material from the serration characteristics. For example, the serration characteristics contain information about the mechanisms of plastic deformation and the structural evolution during deformation. However, due to many factors affecting the serration behavior and some uncertain or uncontrolled factors, it’s a difficult task to give a unified picture of a vast amount of serration data. This review article summarizes the results of previous studies in this rapidly-developing field, attempting to provide a new perspective in expounding the connection between macroscopic properties and micro-mechanisms.In this review paper, serration behavior of a wide range of materials will be discussed. One of the most important goals is to investigate the factors influencing serration characteristics and deformation mechanisms. Several statistical properties, such as distributions of stress drop sizes and waiting times, are reviewed and used to quantify the serration behavior. Moreover, models and theories on the serrated flow will be discussed, which quantify the deformation mechanism and provide physical intuition for the experiments, and methods to organize experimental data. Besides discussing serrations in stress-strain curves of many solid materials, this review paper will also cover other systems with serrations and collective noise, such as crackling noise in the earth’s crust (earthquakes), volume fluctuations in a granular medium and jamming behavior in random-packing systems.

Comparative dynamic evaluation of the sliding/characteristics of the Gamma nail: a biomechanical analysis.

This study was directed at establishing the influence of dynamic loading situations on the sliding characteristics of the Gamma locking nail (Howmedica). It was postulated that the changing regions of load contact area that occur within the sliding mechanism during flexion and extension would favourably modify the jamming behaviour observed under static test conditions. The forces required to initiate sliding of the lag screw in the intramedullary device were investigated under a range of conditions representing clinical situations. The optimum sliding performance of the Gamma nail was shown to occur during test conditions of dynamic loading, when the rate of application of the load was rapid and the cyclic angle of flexion was greatest. The size and weight of the patient also influence the sliding characteristics, as a shorter lag screw length protruding from the barrel and a reduced vertical static load (body weight) yielded a lower axial sliding force. The results under dynamic loading conditions suggest that static testing of sliding hip screws does not accurately represent their clinical performance.

The jamming avoidance response ofEigenmannia: properties of a diencephalic link between sensory processing and motor output

Brain regions participating in the control ofEigenmannia's electric organ discharge frequency were localized by electrical microstimulation and anatomically identified by means of horseradish peroxidase deposition. A diencephalic region was found which, when stimulated, caused electric organ discharge (EOD) frequency increases of similar magnitude and time course as the frequency increases seen during the jamming avoidance response. Single unit recordings from this region revealed one cell type which preferentially responded to stimuli that cause the acceleration phase of the jamming avoidance response (electric organ discharge frequency increase). A second cell type responded preferentially to stimuli which cause EOD frequency decrease, and both cell types were tuned to stimuli which evoked maximal jamming avoidance behaviors.

Spontaneous discharge rhythms and social signalling in the weakly electric fish Pollimyrus isidori (cuvier et valenciennes) (Mormyridae, Teleostei)

The electric organ discharge (EOD) signalling of isolated and of socially interacting Pollimyrus isidori was analyzed. 1. EOD interval histograms of resting animals showed wide ranges with three modes of 12 to 15 ms, of around 92 ms, and of 220 to 230 ms (Fig. 4a). In number and/or position of modes, the P. isidori histograms were clearly different from those shown by four other mormyrid species: Gnathonemus petersii, Mormyrus rume, Brienomyrus niger, Brienomyrus brachyistius. 2. The EOD interval histograms of swimming P. isidori (Fig. 4a) displayed only one mode of around 50 ms and closely resembled the EOD activity exhibited by G. petersii, B. niger, and B. brachyistius. 3. During overt attack (Figs. 4b, 6, 7a), P. isidori displayed high discharge rates as do G. petersii, B. niger, and M. rume. The EOD time patterns of the displays were clearly distinct from the other species' displays. 4. These data suggest the possibility that mormyrids might recognize conspecifics from their resting- or attack-associated EOD time patterns, not, however, by monitoring EOD swimming activity. During this behavior, species identification would seem possible only by the analysis of spectral cues from the properties of the individual EOD pulses (cf. Fig. 3). Compared with the other species mentioned above, the extremely short EOD of P. isidori contains much more energy in a high frequency band (peak: 10 kHz with energy beyond 30 kHz). 5. Different individuals of P. isidori displayed either a Preferred Latency Response of approx. 12 to 14 ms or a response consisting in avoiding a 10 to 20 ms discharge latency to foreign electrical stimuli (Figs. 8–10). While the avoidance response may be considered a jamming avoidance behaviour, reducing the probability of coincidences with a conspecific's EODs, the Prefered Latency Response in P. isidori would have the opposite effect and ‘jam’ a conspecific's signals when the latter displays high discharge rates occurring during attack behaviour. Whether these alternative types of latency behaviour are sex, age, or rank correlated remains to be investigated.