Vystantis technologijoms, prieš apytiksliai aštuonerius metus buvo už patentuota nauja tinklo rūšis - bevielis tinklas. Pastebėjus jų privalumus buvo pradėti sparčiai vystyti . Sparčiai jiems populiarėjant išryškėjo kolizijos problema.Siekiant daugiau apie tai sužinoti buvo iškeltas darbo tikslas - išnagrinėti kolizines situacijas, pateikiant jų pasekmes, vengimo galimybes.Siekiant šio tikslo išnagrinėti populiariausi tinklų tipai. Eksperimentiškai įvykdytos dvi populiariausios kolizinės situacijos. Apžvelgti jau taikomi, bei taikytini, kolizinių situacijų vengimo būdai. Atlikus visas išsikeltas užduotis prieita prie išvados: Norint sumažinti kolizijų kiekį, pagerinti tinklo pralaidumą, pratęsti mobilaus prietaiso energijos šaltinio gyvavimo laiką (energijos suvartojimo kiekį) siūlau „paskleisti“ vartotojus (sudarinėti kiek į manoma mažiau vartotojų turinčius tinklus).Pvz. nagrinėtame WLAN centralizuotos tipologijos koliziniame atvejyje, reikia išdėstyti daugiau kreipties taškų AP. Taip būtų mažinamas vartotojų kiekis vienam AP. Bluetooth „ad hoc“ tipologijai, turint kitokią struktūrą , šis pasiūlymas tiktų turint ne mažiau kaip tris vienu laiko momentu aktyvius prietaisus. / By developing the technologies, approximately eight ears ago a new way of network where found and patented – wireless network. After seeing the advantages of these networks, they started fast development. As wireless network started to be more and more popular a problem of collisions in it started to give more concern. In order to know more about collisions and the way of collision appearance, the task of thesis was to – inspect the situations of collision, bring out the consequences, possible avoidance of it. Seeing this goal most of popular wireless networks where investigated. Reasons of collisions, experimentally explored situations for collisions, possibilities of resolving it where reviewed. After doing all this work, it can be concluded: To lower possible collision rate, ensure better throughput, make longer life time to mobile station (save energy) spreading of users (make smaller networks, with lower quantity of mobile users) might be a way. For example: in case of collision in analyzed WLAN central topology, we would need to add extra access points. That‘s would lower quantity of users per AP. Bluetooth „ad hoc“ topology is different in structure so this proposal would be valid just when minimum three active devices are in a range.

Stacking interactions, also known as π-π or face-to-face interactions, occur between molecules whose π bonds are in parallel planes. They are used to design self-assembling structures in nanotechnology, influence organic reactions and are ubiquitous in nature. The stacking interactions of substituted benzene heterodimers and substituted benzene-natural nucleobase heterodimers are examined. Both electron-donating and withdrawing groups are studied by varying their type, number and location around the benzene ring. The studies are done by carrying out systematic scans of the potential energy surface at the MP2/6-31G*(0.25) level of theory. Charge transfer interactions and extent of charge separation in the monomer are found to be dominant when the difference in ESP between the monomers is large and small, respectively. Dipole-dipole interactions are also found to affect stacking interactions. The results from MP2/6-31G*(0.25) are checked against those at the CCSD(T)/CBS limit for select cases and are found to be within 81- 110%. / xii, 166 leaves : ill. ; 29 cm

Experimental and theoretical investigations of highly-excited molecules are presented that advance the current state of knowledge of intramolecular interactions in highly-excited molecular states. A quantitative analysis of intramolecular interactions in excited hydrogen fluoride is presented, in which the rotational levels of the B singlet-Sigma+, v = 29 vibronic level are shown to mix with the corresponding e-parity components of the C singlet-Pi, v = 0 level. Extrapolating the experimentally-derived mixing parameter to the unperturbed limit reveals an unperturbed value of the aF hyperfine parameter of 4132(25) MHz. Coupling energies between the ion-pair curve and long-range asymptotes of covalent states are calculated for a large number of alkali–alkali collision channels, revealing the dependence on the internuclear distance at which the crossing takes place and forming a foundational step for the calculation of cross-sections and rate coefficients for different charge-exchange and other processes. To advance the experimental investigation of these systems, optical instrumentation and associated control systems have been designed and constructed for cooling and trapping lithium in preparation for experimental studies of cold-collisions that will be informed by, and ultimately a test of, some of these calculated ionic–covalent coupling energies. A novel scheme for systematic optimization of peak-locking has been developed and implemented, providing a rigorous assessment of the optimal experimental parameters. A side-of-filter offset-locking scheme was implemented, characterizing and correcting for a previously unexplained offset in the error-signal. A novel calibrated polarimetry scheme is demonstrated, correcting for the primary sources of uncertainty relating to manufacturing tolerances and experimental errors. The calibrated set of polarization measurements is used to examine the purity of the optical polarization state in the light sources to be used for trapping lithium. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2012-01-31 11:30:22.479

No description available.

No description available.

White-tailed deer (WTD) (Odocoileus virginianus) were studied within the Greater Winnipeg Area (GWA) to investigate urban deer home range size, habitat use, and seasonal movement patterns. A comparative analysis was also completed in Riding Mountain National Park (RMNP) in order to assess the similarities and differences between urban and rural deer spatial and temporal movement patterns. The study revealed differences in the spatial land use patterns of these two cohorts with substantially smaller urban WTD monthly and seasonal home range sizes than in RMNP. Building on the findings derived from the animal-borne locational data, an investigation into the human social dynamics associated with the urban deer herd indicated that human behavior heavily influences urban deer movement. Using a critical case study approach, the research investigated the wildlife value orientations and the emotional dispositions associated with the human behavior of intentionally supplying artificial food sources for deer. The spatial and temporal occurrences of urban deer-vehicle collisions (DVCs) and the factors associated with high risk DVC roadways were not random, and human social behavior is correlated to the frequency and location of DVC occurrences in the GWA. This research identifies management strategies to successfully mitigate human-wildlife conflict and the associated human-human conflict within the GWA, as well as the need for, and challenges associated with, an integrated approach to urban wildlife management.

Experiment E683 at Fermi National Accelerator Laboratory (FNAL) in Batavia, Illinois, uses a modular, high-energy sampling calorimeter as the basis of the detector system. This detector provides information on the energy and position of particles that exit a collision of a photon or pion with a target proton. While exiting particles are thought to form what are described as "jets", and several E683 projects involve working with these jets, it has not yet been demonstrated that jets indeed have been detected.The solution proposed here involves demonstrating that E683 data has a statistically significant "jettiness" even in a data sample which has not been biased. Towards this, a data sample was selected based on criteria unrelated to the presumption of jets. Planarity and the Et Flow were chosen as measures of how oblong(jetlike) an event is. The sample was then examined for planarity and Et flow in a number of kinematic ranges and the results demonstrate that over a certain kinematic range, events in our sample are increasingly planar, as we hypothesized. / Department of Physics and Astronomy

The subject of this thesis is the improvement of particle tracking through the identification and correction of small systematic errors in particle "hit" locations due to positioning of tracking detectors. These errors call be as large or larger than the statistical spatial resolution of tracking detectors themselves, and therefore must be corrected. The focus is on identification and correction of errors due to rotations and beam axis translations.An algorithm is developed for use with proportional wire chamber and drift chamber detectors in experiment E683 at the Wideband facility of Fermi National Laboratory. In this experiment, high energy (tens of GeV) particles, primarily mesons, were produced when photons with energies of 40-400 GeV struck a metal or liquid target.At the present time, the method and code developed for this thesis has not been applied to real data, although an analysis of its effectiveness as a function of detector resolution has been investigated with Monte-Carlo simulations. / Department of Physics and Astronomy

Road expansion and increased traffic likely exacerbates barriers to amphibian migration and dispersal. Within British Columbia’s south Okanagan valley there is particular concern that the COSEWIC-listed blotched tiger salamander (Ambystoma mavortium melanostictum) and Great Basin spadefoot (Spea intermontana) are vulnerable to road effects in their annual movements from upland overwintering habitat to lowland breeding areas. My study utilizes a before after control impact approach to assess amphibian movement and population threats across this highway-bisected landscape. Throughout the spring and summer of 2010-2012, fifty two kilometers of roadways (31 km of highway, 21 km of paved backroad) were repeatedly surveyed from the Canada-USA border to north of Oliver, BC; surveys were carried out utilising vehicles and on foot. Along Highway 97, a three kilometer four-lane highway expansion project was constructed through 2010 and open to traffic use in 2011. Adjacent to a floodplain, survey effort was focused throughout this transect for informed roadkill mitigation structure placement and ongoing ecopassage effectiveness monitoring. Automated camera trap monitoring of culverts within highly concentrated amphibian road hotspots during spring and summer 2011 (three culverts) and 2012 (two culverts) resulted in over eight hundred amphibian culvert events observed. Two sample Wilcoxon tests revealed differences between years in amphibian occurrence between 2010 and 2012 (W = 4679.5, p= 0.02), and mortalities among transect areas, with the largest differences between years within the Osoyoos passing lanes transect. Amphibian mortalities within the passing lanes transect were significantly reduced with the implementation of mitigation structures (x̅2010= 13.2 ± 32.5, x̅2011= 4.7 ± 12.8, x̅2012= 2.3 ± 7.3; 2010 vs. 2012: W= 1535.5, p< 0.001). Roadkill mitigation structures proved effective in observed amphibian occurrence of the entire passing lanes stretch as well as at distances 100 m and 200 m from observed culverts. Double fenced areas resulted in a 94% reduction in amphibian road occurrence. Five species of amphibians were observed over the three survey years (4051 road incidences over 657 survey hours): Pacific chorus frog (Pseudacris regilla), Western toad (Anaxyrus boreas), long-toed salamander (Ambystoma macrodactylum) plus blotched tiger salamander and Great Basin spadefoot. This study aims to provide a better understanding of amphibian hotspots on roadways and ecopassage use within the south Okanagan. It may act as a catalyst to further wildlife-vehicle interaction studies with improved mitigation solutions for amphibian roadway fatalities.

The current study addresses the stability of shock waves propagating through dissipative media, analogous to both granular media and molecular gases undergoing endothermic reactions. In order to investigate the stability, a simple molecular dynamics model was developed to observe shock waves and their structures with the inclusion of energy dissipation. For this, an Event Driven Molecular Dynamics model was implemented in a 2D environment, where a molecule is represented by a disk. The simulations addressed the formation of a shock wave in a gas by the sudden acceleration of a piston. Inelastic collisions were assumed to occur only if an impact velocity threshold is surpassed, representing the activation energy of the dissipative reactions. Parametric studies were conducted for this molecular model, by varying the strength of the shock wave, the activation threshold and the degree of inelasticity in the collisions. The resulting simulations showed that a shock structure does indeed become unstable with the presence of dissipative collisions. This instability manifests itself in the form of distinctive high density non-uniformities behind the shock wave, which take the form of convective rolls. The spacing and size of this ``finger-like" unstable pattern was shown to be dependent on the degree of inelasticity, the activation energy, and the strength of the driving piston. The mechanism responsible for the instability was addressed by studying the time evolution of the material undergoing the shock wave compression and further relaxation. It is found that the gas develops the instability on the same time scales as the clustering instability in homogeneous gases, first observed by Goldhirsch and Zanetti in granular gases. This confirmed that the clustering instability is the dominant mechanism.