We calculate the probability of destruction of a metastable string by collisions of the Goldstone bosons, corresponding to the transverse waves on the string. We find a general formula that allows to determine the probability of the string breakup by a collision of arbitrary number of the bosons. We find that the destruction of a metastable string takes place only in collisions of even number o...

The paper presents a navigation algorithm for dynamic, uncertain environment. The static environment is unknown, while moving pedestrians are detected and tracked on-line. The planning algorithm is based on an extension of the Rapidly-exploring Random Tree algorithm, where the likelihood of the obstacles trajectory and the probability of collision is explicitly taken into account. The algorithm...

Shin et al.[4] proposed a new hash function with 160-bit output length at PKC’98. Recently, at FSE 2002, Han et al.[5] cryptanalyzed the hash function proposed at PKC’98 and suggested a method finding a collision pair with probability 2−30, supposing that boolean functions satisfy the SAC(Strict Avalanche Criterion). This paper improves their attack and shows that we can find a collision pair f...

We consider the challenges posed by dangerous asteroids that make a sequence of close encounters, such as asteroid 99942 Apophis which passes very close to Earth in 2029 and is considered a possible impacter at many subsequent encounters. In particular, we evaluate the energy costs for possible pre-2029 missions, and we also study refined methods to compute probability of collision. We find two...

Hepatocellular carcinoma is one of the most common malignancies worldwide, with a high risk of portal vein tumor thrombus (PVTT). Some promising results have been achieved for venous metastases of hepatocellular carcinoma; however, the etiology of PVTT is largely unknown, and it is unclear why the incidence of PVTT is not proportional to its distance from the carcinoma. We attempted to address ...

We analytically prove that the error in the channel idle time-based collision probability estimation in face of non-saturated stations is bounded by 2/(CWmin+1) in the IEEE 802.11 wireless LANs (WLANs). This work explicitly quantifies the impact of non-saturation, and the result vindicates the use of the estimation technique in real-life IEEE 802.11 WLANs, in such applications as the acknowledg...

Two synchronous transmission multi-channel multi-access protocols for high-speed network architecture are studied in this paper. Analytic discrete time Markovian models are developed for finite number of stations and finite number of channels for the symmetric and asymmetric access rights proposed protocols. The effect of receiver collision phenomenon is examined and analyzed on the performance...

In cognitive radio network, spectrum sensing methods detect the existence of primary users to utilize spectrum holes for secondary users. When it is found that there are no busy primary users then secondary users are allowed to transmit through the spectrum. During the transmission process of secondary users, there may be collision between secondary users. This leads to decrease in the throughp...

In this paper we propose a slotted carrier sense multiple access with collision avoidance (CSMA/CA) DFT (Delayed -First-Transmission) protocol with pulse signal transmission for integrated voice and data transmissions in wireless LAN (WLAN) communication systems. CSMA/CA protocol with pulse signal transmission enables a user having a packet ready to transmit initially some pulse signals with ra...

The main contributions of this paper are two-fold. Firstly, we present a novel direction in the cryptanalysis of the cryptographic hash function SHA-1. Our work builds on previous cryptanalytic efforts on SHA-1 based on combinations of local collisions. Due to dependencies, previous approaches used heuristic corrections when combining the success probabilities and message conditions of the indi...