While frictionless spheres at jamming are isostatic, frictional spheres at jamming are not. As a result, frictional spheres near jamming do not necessarily exhibit an excess of soft modes. However, a generalized form of isostaticity can be introduced if fully mobilized contacts at the Coulomb friction threshold are considered as slipping contacts. We show here that, in this framework, the vibra...

Signal evolution in social animals has produced a wide variety of communal displays, many of them remarkable feats of complex coordination. The two main explanations for this temporal precision are: (1) it evolves as a cooperative signal of coalition quality or (2) it minimizes signal jamming (i.e., interference of one signal by another). However, support for the first hypothesis is inconclusiv...

We numerically study the jamming transition of frictionless polydisperse spheres in three dimensions. We use an efficient thermalisation algorithm for the equilibrium hard sphere fluid and generate amorphous jammed packings over a range of critical jamming densities that is about three times broader than in previous studies. This allows us to reexamine a wide range of structural properties char...

Wireless Sensor Network (WSN) is an emerging technology for various applications public sector, private sector and military. It formed by a large number of networked sensing nodes. It contains of many sensor devices to cooperatively monitor selected target locations and communicate with base stations. Due to the different requirements of large-scale and realtime data processing in WSNs, provide...

Defense against denial of service (DoS) attacks is a critical component of any security system as these attacks can affect the availability of a node or an entire network. In this work, we focus on jamming type DoS attacks at the physical and MAC layers in 802.11 based ad hoc networks. Collisions in wireless networks occur due to varying factors such as jamming attacks, hidden terminal interfer...

By using smart radio devices, a jammer can dynamically change its jamming policy based on opposing security mechanisms; it can even induce the mobile device to enter a specific communication mode and then launch the jamming policy accordingly. On the other hand, mobile devices can exploit spread spectrum and user mobility to address both jamming and interference. In this paper, a two-dimensiona...

With the increasing volume of wireless traffic that military operations require, the likelihood of transmissions interfering with each other is steadily growing to the point that new techniques need to be employed. Furthermore, to combat remotely operated improvised explosive devices, many ground convoys transmit high-power broadband jamming signals, which block both hostile as well as friendly...

We expose a relationship between jamming and a generalization of Tutte’s barycentric embedding. This provides a basis for the systematic treatment of jamming and maximal packing problems on two-dimensional surfaces.

We investigate universal features of the jamming transition in granular materials, colloids and glasses. We show that the jamming transition in these systems has common features: slowing of response to external perturbation, and the onset of structural heterogeneities.

In emerging network systems, such as e-healthcare and smart grids, have been drawing increasing attention in both industry and academia. The broadcast nature of wireless channels unavoidably exposes such applications to jamming attacks. However, existing methods to characterize and detect jamming attacks cannot be applied directly to time-critical networks, whose communication traffic model dif...