The control of excessive water production in oil and gas producing wells is of increasing importance to the field operator, primarily when trying to maintain the survivability of a mature field from shut in. During the last two decades many chemicals have been studied and applied under the name of relative permeability modifier (RPM) to combat this problem. These chemicals were mostly bullheaded individually into the affected zones, consequently their application resulted in low to medium success, particularly in treating reservoirs suffering from matrix flow. It has been found that the disproportionate permeability reduction depends on the amount of polymer dispersed or absorbed by the porous rock. If single polymers are employed to treat excessive water production in a matrix reservoir they cannot penetrate deep into the formation rock because the polymer will start to build as a layer on the surface of the rock grains. As a result the placement of polymer into the formation will no be piston like and the dispersion over the rock pores will be uneven. To improve water shutoff technology a method of injecting chemicals sequentially is recommended provided that the chemical’s viscosity is increasing successively with the chemicals injected. / Experimentally confirmed, injecting chemicals sequentially provides better results for conformance control. The value of post treatment water mobility is conspicuously lowered by the method of applying injecting chemicals sequentially in comparison with the single chemical injection method. For instance, the residual resistance factor to water (Frrw) at the first cycle of brine flushing for this method is approximately five times higher than the Frrw obtained by injecting only one single chemical. Furthermore, for the second cycle of brine flushing Frrw is still higher by a ratio of about 2.5. In addition to this improvement residual resistance factor to oil Frro for this method is less than two which has been considered as the upper limit for conformance control in matrix reservoir. Accordingly injecting chemical sequentially can be applied for enhancing relative permeability modifier performance in matrix reservoir.

Innovation in photovoltaic technology may offer cost competitive options to other energy sources and become a viable solution for the energy and environmental challenges of the 21st century. One proposed innovative technology is based on all-silicon tandem cells, which are constructed using superlattices consisting of environmental friendly Si and its compounds. The well and barrier materials in superlattices are restricted to silicon and silicon oxide during the present study. Single crystalline Si/SiO2 quantum wells (QWs) have been fabricated by thermal oxidation of silicon-on-insulator (SOI) wafers. It is found that oxide properties in QWs are important for SOI wafers prepared by the SIMOX (Separation by Implantation of Oxygen) technique. However, QWs fabricated from SOI wafers prepared by the ELTRAN (Epitaxial Layer TRANsfer) approach show the effect of quantum confinement without evidence of strong oxide interfacial transitions. In these wafers, evidence for an apparently ordered silicon oxide was found with 1.92?atomic fringe spacing along the (110) direction of the Si structure and with the thickness about 17?along the (100) direction of the Si structure. Luminescence wavelength ranges are from 700nm to 918nm depending on the Si thickness. The luminescence measurements on other positions of the sample show peak and shoulder spectra, which are explained by monolayer fluctuations in QW thicknesses, previously observed in III-V QWs and II-VI QWs. Si/SiO2 superlattices are fabricated by RF magnetron sputtering. Si density is the key issue in crystallizing the superlattice. High-density Si layers crystallize either under high temperature furnace annealing or rapid thermal process annealing. However, low density Si would not crystallize even at high temperature. Crystallized nanocrystals in the Si layers are observed by high resolution transmission electron microscopy (HRTEM) when the Si layer is thicker than 3nm. When Si layers are thinner than 3nm, the Si layers are discontinuous and finally deteriorate into small nanocrystals. The suitability of such superlattices for surface passivation and antireflection coatings is reviewed. Initial attempts to fabricate heterojunctions between Si wafers and Si/SiO2 superlattices resulted in open circuit voltage of 252mV. However, it is expected that better results would be obtained if Si/SiO2 superlattices were fully crystallized.

The present thesis is a study of the evolution of defect states in devices based on wide bandgap semiconductors. The attention has been focused on light-emitting diodes based on GaN and Schottky diodes based on SiC, these latter a basic structure for the fabrication of high-power rectifiers and ionising particle detectors. In both cases, we studied the defects and their electronic properties by means of the following experimental techniques: current-voltage (I-V) measurements, in order to investigate the effect of imperfections on the transport properties of the material/device; capacitance-voltage (C-V) measurements, yielding the profile of concentration of charge carriers, and giving information on the influence of defects on this concentration; deep level transient spectroscopy (DLTS), a technique allowing for the identification and characterization of defect-originated electron levels in the gap. I also employed techniques, such as photocurrent spectroscopy (PC), allowing for the characterization of light absorption by the material and/or device versus varying photon energy. In both cases of SiC and GaN, the defect characterization was always interpreted in the framework of its influence on device operation. In the analysed LEDs the defect evolution was connected to the evolution of quantum efficiency, and in the SiC diodes we studied the effects of defect introduction on the charge collection efficiency (CCE) and on the leakage current of the device. Furthermore, for the interpretation of photocurrent spectra, I developed a model describing the generation of photocurrent considering the dispersion relations for the absorption coefficient and refractive index in the various device layers, as well as the internal reflection, transmission and interference phenomena involving the optical field within the device. The research yielded various interesting results: I detected many deep levels introduced by proton- and electron-irradiation in SiC. From the study of their annealing behaviour I concluded that one of these levels is related to a particular lattice defect, the carbon interstitial. By means of the analysis of the introduction rates of the levels and comparisons between proton and electron irradiation, I was able to distinguish between deep levels related to simple intrinsic defects and to defect complexes. In the case of the GaN LED, I found that the evolution of several independent properties are strongly correlated, meaning that a single degradation mechanism is responsible for the observed changes. In particular, I concluded that the degradation of the light emission intensity is due to the generation of defects in the active region of the device.

<p>Föreliggande effektivitetsstudie med individuell KBT-behandling för 17 diagnostiserade socialfobipatienter genomfördes på två allmänpsykiatriska öppenvårdsmottagningar under en period av 18 månader. Syftet med studien är att utvärdera effekten av en KBT-behandling. Alla patienter uppfyllde kriterierna för social fobi enligt DSM-IV. Patienterna erbjöds en behandling med upp till 14 sessioner plus möjlighet till tre uppföljningssamtal. KBT-behandlingen har varit tidseffektiv och deltagarna har framfört positiva synpunkter om samarbetet med terapeuten och de uppnådda målsättningarna i behandlingen. Resultaten visar statistiskt signifikanta förbättringar i samtliga använda mått; BAI, BDI, SPS, LSAS, SIAS. Resultaten visar också måttlig effektstorlek.</p>

<p>The conventional view on the Kalahari in southern Africa expresses that the area is unsuitable for livestock herding. For this reason, it is argued that livestock herders avoided the Kalahari in the past and were only able to establish themselves in the later half of the twentieth century, when deep-reaching boreholes were introduced in the area. An effect of this concept was that the archaeological record of pastoralists in the Kalahari either was perceived as non-existent or received little attention from scientific enquiry.</p><p>Based on an archaeological survey in the Kalahari of the northeastern part of Namibia, the purpose of this study is to construct an alternative approach to the archaeology of livestock herding. The aim is to contribute to a better understanding of the areas unrecorded land-use history. </p><p>I depart from the notion that the main ecological constraint for dryland pastoralism is the availability of dry season water and fodder resources. For this reason, the fundamental basis for a pastoral land-use system is places that contain dry season resources. By reviewing recent ecological research, historical and anthropological accounts and previous archaeological research, I establish a link between livestock herders’ procurement of dry season key resources and the practice of digging wells. The link can be motivated from the pastoral ambition of accumulating livestock and high water requirements in the restrained dry season. On this basis, I suggest that artificial wells are useful indicators of pastoral land use in the Kalahari. </p><p>The most crucial task for the study is to address the archaeological visibility of pastoral well sites. By a research approach integrating the theoretical understanding of pastoralism and a methodology including ecology, archaeology, history and the knowledge of the people who keep livestock in the region today, the archaeological survey revealed 40 well sites, including nearly 200 well structures that have all been used for watering livestock. </p><p>However, it would be unfortunate if a study of pastoral wells would solely address the ecological foundation and the archaeological visibility of pastoralism. I suggest that the wells signify the labour of peoples with common or separate histories, with or without own herds, but probably talked about in relation to herds. I will also argue that the wells can be used for tracking and reconstructing a pastoral land-use system that predated the colonial era. Furthermore, the wells can be used to identify changes of the land-use that took place during the twentieth century, which involved that livestock herding was more or less abandoned in large parts of northwestern Kalahari. </p><p>The study surmises that the critical historical perspective is valuable for development projects and conservationist interventions active in the region, especially in the light of the recent trends in the dryland ecology, which shows a larger appreciation for the indigenous understanding of the management of dryland ecosystems. With modifications, the developed approach can be applicable for land-use historical research elsewhere in southern Africa.</p>

<p>The Orange Basin was formed during the late Jurassic to early Cretaceous periods due to Gondwana breakup and rifting and later drifting apart of the African and South American plates. The basin consists of siliciclastic sandstone which took its sediment supply from river system with a rivalling delta to the north of the basin. Geological and petrophysical studies were carried out to evaluate the reservoir potential of the wells in the study area. This study considered five wells (A-G1, A-W1, A-K1, A-K2 and A-Y1) in the Orange Basin with attention to the Albian age sandstone. Only three of the studied wells (A-G1, A-W1 and A-K1) have core samples for analysis. The methods used for the execution of this study include the description and calibration of spot cores with conventional standard logging record responses, wireline log interpretation using sequence stratigraphy approach, detailed petrographic (SEM, HR-TEM, XRD and thin section) and geochemical (pore water geochemistry, FTIR and XRF) analyses, and petrophysical analysis to unravel the complexities with regard to facies association, depositional environment and diagenesis. Linking diagenesis to depositional facies and sequence stratigraphy has given a clearer picture to the spatial and temporal distribution of diagenetic alterations and thus of evolution of reservoir quality in the studied wells. Three depositional lithofacies were identified based on a detailed core description [fine grained sandstone (F1), very fine grained sandstone (F2) and mudstone (F3)]. Fluvio-deltaic and shallow marine environments were also interpreted from the core description based on the sedimentary structures and mineral assemblage while the log interpretation shows that the different reservoir units range between LST, TST and HST but mostly of LST. Mineralogical predictions were made possible in the wells without core samples (A-K2 and A-Y1) through the use of density-neutron cross plot, these reveal that the two wells contain some considerable amount of clay minerals like kaolinite, chlorite and illite.</p>

Vertical cavity lasers (VCLs) are of great interest aslow-cost, high-performance light sources for fiber-opticcommunication systems. They have a number of advantages overconventional edge-emitting lasers, including low powerconsumption, efficient fiber coupling and wafer scalemanufacturing/testing. For high-speed data transmission overdistances up to a few hundred meters, VCLs (or arrays of VCLs)operating at 850 nm wavelength is today the technology ofchoice. While multimode fibers are successfully used in theseapplications, higher transmission bandwidth and longerdistances require single-mode fibres and longer wavelengths(1.3-1.55 µm). However, long-wavelength VCLs are as yetnot commercially available since no traditional materialssystem offers the required combination of bothhigh-index-contrast distributed Bragg reflectors (DBRs) andhigh-gain active regions. Earlier work on long-wavelength VCLshas therefore focused on hybrid techniques, such as waferfusion between InP-based QWs and AlGaAs DBRs, but more recentlythe main interest in this field has shifted towardsall-epitaxial GaAs-based devices employing novel 1.3-µmactive materials. Among these, strained GaInNAs/GaAs QWs aregenerally considered one of the most promising approaches andhave received a great deal of interest. The aim of this thesis is to investigate monolithicGaAs-based long-wavelength (&gt;1.2 µm) VCLs with InGaAsor GaInNAs QW active regions. Laser structures - or partsthereof - have been grown by metal-organic vapor phase epitaxy(MOVPE) and characterized by various techniques, such ashigh-resolution x-ray diffraction (XRD), photoluminescence(PL), atomic force microscopy, and secondary ion massspectroscopy (SIMS). High accuracy reflectance measurementsrevealed that n-type doping is much more detrimental to theperformance of AlGaAs DBRs than previously anticipated. Asystematic investigation was also made of the deleteriouseffects of buried Al-containing layers, such as AlGaAs DBRs, onthe optical and structural properties of subsequently grownGaInNAs QWs. Both these problems, with their potential bearingon VCL fabrication, are reduced by lowering the DBR growthtemperature. Record-long emission wavelength InGaAs VCLs were fabricatedusing an extensive gain-cavity detuning. The cavity resonancecondition just below 1270 nm wavelength occurs at the farlong-wavelength side of the gain curve. Still, the gain is highenough to yield threshold currents in the low mA-regime and amaximum output power exceeding 1 mW, depending on devicediameter. Direct modulation experiments were performed on1260-nm devices at 10 Gb/s in a back-to-back configuration withopen, symmetric eye diagrams, indicating their potential foruse in high-speed transmission applications. These devices arein compliance with the wavelength requirements of emerging10-Gb/s Ethernet and SONET OC-192 standards and may turn out tobe a viable alternative to GaInNAs VCLs. <b>Keywords:</b>GaInNAs, InGaAs, quantum wells, MOVPE, MOCVD,vertical cavity laser, VCSEL, long-wavelength, epitaxy, XRD,DBR

The conventional view on the Kalahari in southern Africa expresses that the area is unsuitable for livestock herding. For this reason, it is argued that livestock herders avoided the Kalahari in the past and were only able to establish themselves in the later half of the twentieth century, when deep-reaching boreholes were introduced in the area. An effect of this concept was that the archaeological record of pastoralists in the Kalahari either was perceived as non-existent or received little attention from scientific enquiry. Based on an archaeological survey in the Kalahari of the northeastern part of Namibia, the purpose of this study is to construct an alternative approach to the archaeology of livestock herding. The aim is to contribute to a better understanding of the areas unrecorded land-use history. I depart from the notion that the main ecological constraint for dryland pastoralism is the availability of dry season water and fodder resources. For this reason, the fundamental basis for a pastoral land-use system is places that contain dry season resources. By reviewing recent ecological research, historical and anthropological accounts and previous archaeological research, I establish a link between livestock herders’ procurement of dry season key resources and the practice of digging wells. The link can be motivated from the pastoral ambition of accumulating livestock and high water requirements in the restrained dry season. On this basis, I suggest that artificial wells are useful indicators of pastoral land use in the Kalahari. The most crucial task for the study is to address the archaeological visibility of pastoral well sites. By a research approach integrating the theoretical understanding of pastoralism and a methodology including ecology, archaeology, history and the knowledge of the people who keep livestock in the region today, the archaeological survey revealed 40 well sites, including nearly 200 well structures that have all been used for watering livestock. However, it would be unfortunate if a study of pastoral wells would solely address the ecological foundation and the archaeological visibility of pastoralism. I suggest that the wells signify the labour of peoples with common or separate histories, with or without own herds, but probably talked about in relation to herds. I will also argue that the wells can be used for tracking and reconstructing a pastoral land-use system that predated the colonial era. Furthermore, the wells can be used to identify changes of the land-use that took place during the twentieth century, which involved that livestock herding was more or less abandoned in large parts of northwestern Kalahari. The study surmises that the critical historical perspective is valuable for development projects and conservationist interventions active in the region, especially in the light of the recent trends in the dryland ecology, which shows a larger appreciation for the indigenous understanding of the management of dryland ecosystems. With modifications, the developed approach can be applicable for land-use historical research elsewhere in southern Africa.

Föreliggande effektivitetsstudie med individuell KBT-behandling för 17 diagnostiserade socialfobipatienter genomfördes på två allmänpsykiatriska öppenvårdsmottagningar under en period av 18 månader. Syftet med studien är att utvärdera effekten av en KBT-behandling. Alla patienter uppfyllde kriterierna för social fobi enligt DSM-IV. Patienterna erbjöds en behandling med upp till 14 sessioner plus möjlighet till tre uppföljningssamtal. KBT-behandlingen har varit tidseffektiv och deltagarna har framfört positiva synpunkter om samarbetet med terapeuten och de uppnådda målsättningarna i behandlingen. Resultaten visar statistiskt signifikanta förbättringar i samtliga använda mått; BAI, BDI, SPS, LSAS, SIAS. Resultaten visar också måttlig effektstorlek.

This study discusses how the literary device of time travel can limit or empower protagonists. The main focus is on H.G. Wells The Time Machine and the two films of the same name inspired by the novel. The popularity of time travel in film springs from the myriad storytelling possibilities the device provides, and the writers agenda determines what place, if any, logic and causality have in the story. Some narratives endorse the theory of eternalism, where time is fixed and the time travellers actions are fated to be consistent with the history the traveller knows. But many films rely on theories of multiple timelines and many worlds, giving the traveller a much greater range of agency. Paradoxes of causality can inhibit the travellers actions as well. This essay discusses the broad spectrum in time travel narrative, where at one end travellers are imprisoned in history, and at the other they enjoy a great deal of freedom.