The sixth-generation (6G) of wireless communication systems will significantly rely on fog/edge network architectures for service provisioning. To satisfy stringent quality of service requirements using dynamically available resources at the edge, new network access schemes are needed. In this paper, we consider a cognitive dynamic edge/fog network where primary users (PUs) may temporarily share their resources and act as fog nodes for secondary users (SUs). We develop strategies for distributed dynamic fog probing so SUs can find out available connections to access the fog nodes. To handle the large-state space of the connectivity availability that includes availability of channels, computing resources, and fog nodes, and the partial observability of the states, we design a novel distributed Deep Q-learning Fog Probing (DQFP) algorithm. Our goal is to develop multi-user strategies for accessing fog nodes in a distributed manner without any centralized scheduling or message passing. By using cooperative and competitive utility functions, we analyze the impact of the multi-user dynamics on the connectivity availability and establish design principles for our DQFP algorithm.

Electron densities and collision frequencies were obtained on a number of gases in a dc discharge at low pressures (0.70-2mm of Hg). These measurements were performed by microwave probing of a filament of the dc discharge placed coaxially in a resonant cavity operating in a TM₀₁₀ mode. The equipment and techniques for making the microwave measurements employing the resonant cavity are described. One of the main features of this investigation is the technique of differentiating the resonance signal of the loaded cavity in order to make accurate measurements of the resonant frequency and half-power point frequencies.

Projekt ”Förbifart Stockholm” startade år 2009 och är en av tidernas största projekt i Sverige. Examensarbetet tar upp den geotekniska, hydrologiska och geologiska aspekten kring projektet ”Förbifart Stockholm”. Mer exakt så studerades sättningar på grund av grundvattensänkningar, men också så kallade pågående sättningar. Sättningar undersöktes och beräknades i ett utvalt område i Sätra. Beräkningarna gjordes med olika djup på grundvattensänkningar för att undersöka sättningarnas storlek. Därefter beräknades det hur lång tid det tog för att uppnå slutsättningen.  En noggrann analys av det utvalda området gav en bättre förståelse till varför det pågår sättningar i dagsläget utan att det skett något arbete än. När ett område med pågående sättningar utsätts för en grundvattensänkning så kan det leda till stora markrörelser. Ur resultatet av beräkningarna undersöks det om sättningarna är så pass stora att intilliggande byggnader kan skadas. Om så är fallet måste man minska grundvattensänkningen. Resultatet visade att sättningarna blev så stora att det fanns en risk för skador. Därför har det bestämts att en infiltrationsanläggning ska användas. Med hjälp av den kan en större grundvattensänkning förhindras och på så sätt förebygga skadliga sättningar. Skadliga sättningar kan vara väldigt kostsamma och det vill man undvika vid ett projekt som beräknas kosta ca 28 miljarder kronor. / The project “Förbifart Stockholm” started year 2009 and is one of the biggest projects in Swedish history. The Bachelor takes on the geotechnical, hydrological and geological aspect in project “Förbifart Stockholm”. More exactly it is a study of subsidence due to groundwater lowering, but also so called ongoing subsidence. Subsidence’s were examined and calculated in a chosen area in Sätra. The calculations were done with different groundwater lowering to examine how big the subsidence was. Thereafter new calculations were made to see how long time it took to reach the final subsidence. A thorough analysis of the area in Sätra gave a better understanding to why there are ongoing subsidences when the tunnel digging has not begun yet. When an area with ongoing subsidence undergoes a groundwater lowering it could result in a big ground movement. From the result of the calculations there is an investigation to see if the subsidence is so big it could cause damage to nearby buildings. If that was the case then a method to reduce groundwater lowering must be found. The result indicates that the subsidence could become so big that there is a chance of damaging buildings. Therefore it has been decided to install an infiltration device. The infiltration device helps preventing deeper groundwater lowering and avoiding harmful subsidence. Harmful subsidence can become very costly and needs to be avoided in a project that costs 28 billion Swedish crones.

The gut microbiome and its metabolic processes are dynamic systems. Surprisingly, our understanding of gut microbiome dynamics is limited. Here we report a metaproteomic workflow that involves protein stable isotope probing (protein-SIP) and identification/quantification of partially labeled peptides. We also developed a package, which we call MetaProfiler, that corrects for false identifications and performs phylogenetic and time series analysis for the study of microbiome dynamics. From the stool sample of five mice that were fed with 15-N hydrolysate from Ralstonia eutropha, we identified 15,297 non-redundant unlabeled peptides of which 10,839 of their heavy counterparts were quantified. These peptides revealed incorporation profiles over time that were different between and within taxa, as well as between and within clusters of orthologous groups (COGs). Our study helps unravel the complex dynamics of protein synthesis and bacterial dynamics in the mouse gut microbiome.

Background. Detecting malware command and control infrastructure has impor-tant applications for protecting against attacks. Much research has focused on thisproblem, but a majority of this research has used traffic monitoring methods fordetection. Objectives. In this thesis we explore methods based on network scanning and active probing, where detection is possible before an attack has begun, in theory resulting in the ability to bring the command and control server down preemptively. Methods. We use network scanning to discover open ports which are then fed into our probing tool for protocol identification and data gathering. Fingerprinting is performed on the open ports and running services of each host.We develop two methods for fingerprinting and classification of hosts. The first method uses a machine learning algorithm over the open ports and probe data, while the other computes distance scores between hosts. We compare these methods to the new but established JARM method for host fingerprinting, as well as to two other simple methods. Results. Our findings suggest that our general active probing method is feasible for use in detecting command and control infrastructure, but that the results vary strongly depending on the malware family, with certain malware families providing much better results than others. Conclusions. We end with discussions on the limitations of our methods and how they can be improved, as well as bring up our opinions on the potential for future work in this area. / Bakgrund. Att kunna upptäcka command-and-control-infrastruktur kopplad till malware har viktiga tillämpningar för syftet att skydda mot attacker. Mycket forskning existerar som fokuserar på detta problem, men en majoritet använder metoder baserade på trafikmonitorering. Syfte. I denna uppsats utforskar vi istället metoder baserade på scanning och probing av nätverk, genom vilka detektering är möjlig innan en attack har ägt rum, med fördelen att en command-and-control-server i teorin kan tas ner förebyggande. Metod. Vi använder nätverks-scanning för att upptäcka öppna portar vilka matas in i vårt probing-verktyg som sedan utför protokoll-identifiering och datainsamling. Vi skapar ett fingeravtryck av varje server från de öppna portarna och de hostade tjänsterna. Två metoder för klassifiering av servrar togs fram. Den första metoden använder en maskininlärningsalgoritm över de öppna portarna och probe-datan, medan den andra beräknar en distans mellan två servrar. Vi jämför dessa metoder med den nya men etablerade JARM-metoden, som tar fram fingeravtryck av servrar från TLS-data, samt med två andra, simplare metoder. Resultat. Våra upptäckter visar att vår metod, som bygger på generell, aktiv probing är möjlig att använda för detektering av command-and-control-infrastruktur, men att resultaten varierar kraftigt beroende på malware-familj, där vissa familjer erbjuder mycket bättre resultat än andra. Slutsatser. Vi avslutar med att diskutera begränsningar i våra metoder och hur dessa kan förbättras, samt tar upp våra åsikter om potentialen för framtida forskning inom detta område.

Multiple mechanisms control bacterial community structure but two in particular, the "legacy" of past environmental conditions, and the "priming" of bacteria to respond to seasonal or reoccurring fluctuations in resources, have the potential to determine both bacterial communities, as well as, temporal shifts in active bacterial taxa. To begin to evaluate the legacy effects of resources on microbial communities, we added four limiting resources annually (i.e., water only; C-mannitol + water; N-NH4NO3 + water; and C, N + water) and measured shifts in bacterial community composition after seven years in a cold desert ecosystem in the McMurdo Dry Valleys, Antarctica. Further, to investigate the ecological significance of priming, we conducted a series of stable isotope probing experiments (i.e., 18O-DNA SIP with 18O-labeled water, 13C-DNA SIP with 13C-labeled mannitol, 15N-DNA with 15N- NH4NO3, and a combined C and N SIP) and characterized the responding (i.e., isotopically labeled) and seed bank (i.e., unlabeled) bacterial communities. We performed each of the SIPs in soil microcosms corresponding to a single resource manipulation (e.g., 13C-labeled mannitol in C addition soils). We hypothesized that all long-term additions of nutrients and water will lead to a distinct bacterial community—a legacy effect due to the nutrient and water impoverished state of Antarctica soils. We also hypothesized that the stronger the legacy effects demonstrated by a specific community the more adapted or primed bacterial species will be to take advantage of the resource and respond. As hypothesized, resource additions created distinct bacterial legacy but to different degrees among the treatments. The extent of the resource legacy effects was greatest in the CN, intermediate in water and N, and lowest in C communities relative to the control communities, suggesting that C induced changes in communities were intensified by tandem N additions and that water alone created a more distinct legacy than water and C additions combined. Contrary to our hypothesis, the stronger the legacy effects, the less adapted or primed the community was to take advantage of resource additions. For example, the CN treatment that induced the greatest effect on bacterial communities had the lowest number of species (20.9%) in common between the responding and seed bank communities. This inverse relationship may be due to only two species (i.e., Arthrobacter, Actinobacteria and Massilia, Betaproteobacteria) really being primed to take advantage of CN and these species constituting over 75% of the seed bank community. Water, N, and C additions had similar levels of priming with 38.4%, 41.4%, and 36.3% of the responding species being present in the seed bank community, respectively. But of these three treatments, only the priming with water resulted in a unique responding community, suggesting that water, a universal bacterial resource, was enough to prime bacteria. Furthermore, water generates the most diverse responding community of all the resources with stemming from all of the fourteen dominant phyla. We did find patterns of ecological coherence among the responders, especially in the major responders (i.e., responders that increased in relative recovery by at least ten-fold). These responders were predominantly found in only three phyla (i.e., Actinobacteria, Bacteriodetes, and Gammaproteobacteria) regardless of resource addition. Alternatively minor responders (i.e., responders that increased in relative recovery at least two-fold) were contained in fourteen different phyla with specific taxa stimulated by CN (i.e., Betaproteobacteria) and N and water (i.e., Deltaproteobacteria). Further, resource additions elicited responses from 37% of bacterial species with species specializing on a specific resource (e.g., Chloroflexi) or being a generalist (e.g., Planctomycetes and Gammaproteobacteria). Our results offer the first direct links between legacy and priming effects on bacterial community composition and demonstrate that these mechanisms are not always complimentary leading to the formation of similar communities but may both be essential to maintain the high levels of bacterial diversity. Further, all resources produced elicited responders that were either specialists of generalists demonstrating that even bacteria in the extreme environment of Antarctica respond to pulses of resources.

No description available.

Laser-plasma-based ion accelerators are becoming a versatile platform to drive different fields of applied research and life sciences, for example translational research in radiation oncology. To ensure stable accelerator performance, complete control over the ion source, i.e., the high-intensity laser-solid interaction, is required. However, idealized interaction conditions are almost impossible to reach, as the utilized high-power lasers always feature a non-negligible amount of light preceding the laser peak. This leading edge of the laser pulse usually exceeds the ionization potential of bound electrons much earlier than the arrival of the high-power laser peak and the solid-density target undergoes significant modifications even before the actual high-intensity laser-plasma interaction starts. Control over this so-called target pre-expansion is a key requirement to achieve quantitative agreement between numerical simulations and experiments of high-intensity laser-solid interactions. This thesis investigates several aspects that are relevant to improve the capability of simulations to model realistic experimental scenarios. The corresponding experiments are conducted with cryogenic hydrogen-jet targets and the DRACO-PW laser at peak intensities between 10^12 W/cm^2 and 10^21 W/cm^2 . The experimental implementation of time-resolved optical-probing diagnostics and technical innovations with respect to the technique of off-harmonic optical probing overcome the disturbances by parasitic plasma self-emission and allow for unprecedented observations of the target evolution during the laser-target interactions. The laser-induced breakdown of solids, i.e., the phase transition from the solid to the plasma state, can be considered as an heuristic starting point of high-intensity laser-solid interactions. As it is highly relevant to simulations of target pre-expansion, Chapter 3 of this thesis presents time-resolved measurements of laser-induced breakdown in laser-target interactions at peak intensities between 0.6 * 10^21 W/cm^2 and 5.7 * 10^21 W/cm^2 . By increasing the peak intensity, a lowering of the applicable threshold intensity of laser-induced breakdown well below the appearance intensity of barrier-suppression ionization occurs. The observation demonstrates the relevance of the pulse-duration dependence of laser-induced breakdown and laser-induced damage threshold to the starting point of high-intensity laser-solid interactions. To apply the results to other laser-target assemblies, we provide a detailed instruction of how to pinpoint the starting point by comparing measurements of the laser contrast with a characterization study of the target-specific thresholds of laser-induced breakdown at low laser intensity. Chapter 4 of this thesis presents an example of how optical-probing diagnostics are able to estimate target pre-expansion as a starting condition for particle-in-cell simulations. The measurement allows to restrict the surface gradient of the pre-expanded plasma density to an exponential scalelength between 0.06 um and 0.13 um. Furthermore, the plasma-expansion dynamics induced by the ultra-relativistic laser peak are computed and post-processed by ray-tracing simulations. A comparison to the experimental results yields that the formation of the measured shadowgrams is governed by refraction in the plasma-density gradients and that the observed volumetric transparency of the target at 1.4 ps after the laser peak is not caused by relativistically induced transparency but by plasma expansion into vacuum instead.

Additive friction stir deposition (AFSD) of AZ31B magnesium alloy was conducted to examine evolution of grain structure, phases, and crystallographic texture. AFSD was carried out using a hollow tool made from tool steel at a constant rotational velocity of 400 rpm on the AZ31B base plate. Bar stock of AZ31B was utilized as a feed material. The linear velocity of the tool was varied in the range of 4.2-6.3 mm/s. The feed rate of the material had to be maintained at a half value compared to the corresponding linear velocity for the successful deposition. The layer thickness and length of the deposits were kept constant at 1 mm and 50 mm respectively. The tool torque and actuator force values were recorded during the process and for calculation of the average input energy for each processing condition. Temperature during the AFSD experiments was monitored using a type k thermocouple located 4 mm beneath the deposition surface at the center of the deposition track. The average input energy values showed a decreasing trend with increasing tool linear velocity. The temperature values during deposition were ∼0.7 times the liquidus of the alloy. The deposited material then was examined by laser microscope and profilometer, X-ray diffraction, scanning electron microscopy, electron back scatter diffraction (EBSC), contact angle measurement and micro hardness tests. The AFSD AZ31B samples showed reduction in areal surface roughness with an increase in the tool linear velocity. The X-ray spectra revealed increase in the intensity of prismatic planes of α-Mg phase with increase in tool linear velocity. AFSD of AZ31B Mg alloy resulted in shifting of the grain size from a broader and courser distribution within the feed material to a tighter distribution. Moreover, EBSD observations confirmed the refinement in grain size distribution as well as the presence of predominantly prismatic texture for the AFSD samples when compared to the feed material. There was a marginal improvement in the hardness for the AFSD samples compared to the feed material. However, there was no significant change in the contact angle measurements in simulated body fluid for the AFSD samples compared to the feed material. The current work demonstrated ability of AFSD technique for the additive fabrication of magnesium-based alloys and provided a methodology for examining various process attributes influencing the processing-structure-property relationship.

No description available.