The quantum mechanical theory of rotational and vibrational transitions in atom-diatom systems is investigated and summarized. The time independent scattering formalism of Arthurs and Dalgarno is used, and the degeneracy-averaged cross section is expressed in terms of the scattering S matrix. The major emphasis is on the solution of the rotationally strongly coupled differential equations. Various methods of solving the scattering equations are examined and some of the inadequacies of these methods are discussed. A strong coupling (SC) approximation, valid for small energy exchange, is introduced and tested numerically on some model problems. A first-order iteration to the SC approximation is presented to improve the SC approximation and to extend the range of validity to cases of larger energy exchange. The SC results are compared with the accurate numerical solution and other approximate methods for some model problems. The comparison clearly demonstrates that the SC approximation is the computationally fastest, reasonably reliable method known for computing rotationally inelastic cross sections.

Intercept feeding was tested for its efficacy in reducing deer-vehicle collision frequency by diverting deer movement patterns away from highways using alfalfa hay as an attractant. Ratios of road kills in control vs. treatment zones of three highway segments indicated that feeding reduced collision frequency. Spotlighting counts of live deer were significantly higher (P

No description available.

The need for multiple access strategies arises whenever a number of users have to share a communication resource, since it is usually either cost prohibitive or impractical to dedicate a communication channel to a particular user. A need for such algorithms arises in many instances, particularly in applications utilizing wireless systems where all users access a common channel or medium. Such random access techniques as ALOHA and slotted ALOHA have been successfully implemented in a number of wireless applications. One of the major drawbacks of these algorithms is the necessity of a return path from the central station to each system user, which makes their use both inefficient and expensive for applications where one-way communication would suffice. For such applications, a need remained for a random access algorithm which can maximize the probability of successful message transmission in a one-way communication environment. A random access technique that addresses the above-mentioned need is developed. With this technique, each user sends an original message of predetermined length to a central receiver. The user then retransmits the message a specified number of times in a predetermined interval reserved for the retransmission process. The time interval between each successive retransmission of a given message is random. Assuming total annihilation of all colliding messages, the expression for the probability of successful transmission of a given message in terms of the major channel parameters is theoretically formulated. This technique offers a significant improvement, compared to a single transmission, in ensuring that a message is successfully received. The actual message collision dynamics in this system are experimentally studied using two different types of direct-sequence spread spectrum receivers, one employing a sliding correlator and the other using a matched filter. The spreading code in such systems offers extra protection for messages against possible interferers. The results indicate that it is often possible to properly receive a given message in the presence of co-channel interferers, thus significantly improving the overall system performance. These results are subsequently incorporated with the propagation data for several different types of microcells to arrive at a more precise theory of the link. / Ph. D.

Broadcasting is an essential and effective data propagation mechanism with several important applications, such as route discovery, address resolution and many other network services. Though data broadcasting has many advantages, it can also cause a high degree of contention, collision and congestion, leading to what is known as ¿broadcast storm problems¿. Broadcasting has traditionally been based on the flooding protocol, which simply overflows the network with a high number of rebroadcast messages until these reach all the network nodes. A good probabilistic broadcast protocol can achieve high saved rebroadcast (SRB), low collision and a lower number of relays. When a node is in a sparse region of the network, rebroadcasting is relatively more important while the potential redundancy of rebroadcast is low because there are few neighbours which might rebroadcast the packet unnecessarily. Further, in such a situation, contention over the wireless medium resulting from Redundant broadcasts is not as serious as in scenarios with medium or high density node populations. This research proposes a dynamic probabilistic approach that dynamically fine-tunes the rebroadcast probability according to the number of neighbouring nodes distributed in the ad-hoc network for routing request packets (RREQs) without requiring the assistance of distance measurements or location-determination devices. The main goal of this approach is to reduce the number of rebroadcast packets and collisions in the network. The performance of the proposed approach is investigated and compared with simple AODV, fixed-probabilistic and adjusted-probabilistic flooding [1] schemes using the GloMoSim network simulator and a number of important MANET parameters, including node speed, traffic load and node density under a Random Waypoint (RWP) mobility model. Performance results reveal that the proposed approach is able to achieve higher SRB and less collision as well as a lower number of relays than fixed probabilistic, simple AODV and adjusted-probabilistic flooding. In this research, extensive simulation experiments have been conducted in order to study and analyse the proposed dynamic probabilistic approach under different mobility models. The mobility model is designed to describe the movement pattern of mobile customers, and how their position, velocity and acceleration change over time. In this study, a new enhanced dynamic probabilistic flooding scheme is presented. The rebroadcast probability p will be calculated dynamically and the rebroadcasting decision will be based on the average number of nodes in the ad-hoc networks. The performance of the new enhanced algorithm is evaluated and compared to the simple AODV, fixed-probabilistic, adjusted-probabilistic and dynamic-probabilistic flooding schemes. It is demonstrated that the new algorithm has superior performance characteristics in terms of collision, relays and SRB. Finally, the proposed schemes are tested and evaluated through a set of experiments under different mobility models to demonstrate the relative merits and capabilities of these schemes.

The Quark-Gluon Plasma (QGP) produced in heavy-ion collisions has been shown to behave like a nearly perfect fluid, characterized by a very low ratio of shear viscosity to entropy density. Significant measurements in large collision systems have improved the constraints on the value of 𝜂/𝑠. However, the precise temperature dependence of 𝜂/𝑠 still remains unknown. The interplay between viscous effects and initial geometry fluctuations is important that requires further investigation. Another key open question in the study of multi-particle production is the relationship between the “ridge” – observed azimuthal correlations between particles in the underlying event that extend over all rapidities – and hard or semi-hard scattering processes in small collision systems. In particular, it is not known whether jets or their soft fragments are correlated with particles in the underlying event. This dissertation presents two analyses. The first analysis measures flow harmonics 𝜈2–𝜈6 in 3 𝜇b^-1 of Xe+Xe collisions at √𝑠𝖭𝖭 = 5.44 TeV using the ATLAS detector at the LHC. The centrality, multiplicity, and 𝑝_T dependence of the 𝜈n values obtained using two-particle correlations and template-fit procedure are presented, and the measurements are compared with those in Pb+Pb collisions and 𝑝+Pb collisions at 5.02 TeV. The 𝜈n values in Xe+Xe collisions are observed to be larger than those in Pb+Pb collisions for n = 2, 3, and 4 in the most central events. However, the 𝜈n values in Xe+Xe collisions become smaller than those in Pb+Pb collisions with decreasing centrality or increasing harmonic order n. The 𝜈n in Xe+Xe and Pb+Pb collisions are also compared as a function of the mean number of participating nucleons and the measured charged-particle multiplicity in the detector. The 𝜈3 values in Xe+Xe and Pb+Pb collisions are observed to be similar at the same ⟨𝑁_part⟩ or multiplicity, but the other harmonics are significantly different. The second analysis studies two-particle correlations in pp collisions at 13 TeV using data collected by the ATLAS experiment at the LHC, with an integrated luminosity of 15.8 pb⁻¹, in two different configurations. In the first case, charged particles associated with jets are excluded from the correlation analysis, while in the second case, correlations are measured between particles within jets and charged particles from the underlying event. Second-order flow coefficients, 𝜈2, are presented as a function of event multiplicity and transverse momentum. These measurements show that excluding particles associated with jets does not affect the measured correlations. Moreover, particles associated with jets do not exhibit any significant azimuthal correlations with the underlying event, ruling out hard processes contributing to the ridge.

The recent emergence of electric scooter (e-scooter) ride share companies has greatly increased the use of e-scooters in cities around the world. In this thesis, firstly, e-scooter injuries reported in the current literature as well as an overview of current e-scooter company policies, state laws, and local laws are reviewed. The most injured regions of the body were the head and extremities. These injuries are generally minor to moderate in severity and commonly include fractures and lacerations. A primary cause of e-scooter accidents is front wheel collisions with a vertical surface such as a curb or object, generically referred to as a "stopper." Therefore, various e-scooter-stopper crashes were simulated numerically across different impact speeds, approach angles, and stopper heights to characterize their influence on rider injury risk during falls. A finite element (FE) model of a standing Hybrid III anthropomorphic test device was used as the rider model after being calibrated against certification test data. The angle of approach was found to have the greatest effect on injury risk to the rider, and it was shown to be positively correlated with injury risk. Smaller approach angles were shown to cause the rider to land on their side, while larger approach angles caused the rider to land on their head and chest. Additionally, arm bracing was shown to reduce the risk of serious injury in two thirds of the impact scenarios. The majority of e-scooter rider fatalities (about 80%) are recorded in collisions between a car and an e-scooter. Therefore, crashes between an e-scooter and a sedan (FCR) and a sports utility vehicle (SUV) were simulated using finite element models. The vehicles impacted the e-scooter at a speed of 30 km/hr in a perpendicular collision and at 15 degrees towards the vehicle, to simulate a rider being struck by a turning vehicle. The risks of serious injury to the rider were low for the head, brain, and neck, but femur/tibia fractures were observed in all simulations. The primary cause of head and brain injuries was found to be the head-ground impact if such an impact occurred. / Master of Science / The recent emergence of electric scooter (e-scooter) ride share companies has greatly increased the use of e-scooters in cities around the world. In this thesis, firstly, e-scooter injuries reported in the current literature as well as an overview of current e-scooter company policies, state laws, and local laws are reviewed. The most injured regions of the body were the head and extremities. These injuries are generally minor to moderate in severity and commonly include fractures and lacerations. A primary cause of e-scooter accidents is front wheel collisions with a vertical surface such as a curb or object, generically referred to as a "stopper." Therefore, various e-scooter-stopper crashes were simulated numerically across different impact speeds, approach angles, and stopper heights to characterize their influence on rider injury risk during falls. A finite element (FE) model of a standing Hybrid III anthropomorphic test device was used as the rider model after being calibrated against certification test data. The angle of approach was found to have the greatest effect on injury risk to the rider, and it was shown to be positively correlated with injury risk. Smaller approach angles were shown to cause the rider to land on their side, while larger approach angles caused the rider to land on their head and chest. Additionally, arm bracing was shown to reduce the risk of serious injury in two thirds of the impact scenarios. The majority of e-scooter rider fatalities (about 80%) are recorded in collisions between a car and an e-scooter. Therefore, crashes between an e-scooter and a sedan (FCR) and a sports utility vehicle (SUV) were simulated using finite element models. The vehicles impacted the e-scooter at a speed of 30 km/hr in a perpendicular collision and at 15 degrees towards the vehicle, to simulate a rider being struck by a turning vehicle. The risks of serious injury to the rider were low for the head, brain, and neck, but femur/tibia fractures were observed in all simulations. The primary cause of head and brain injuries was found to be the head-ground impact if such an impact occurred.

No description available.

No description available.

No description available.