Characterization of Soft Clays and the Response of Soil Foundation Systems for Offshore Applications

The overwhelming bulk of our population, about 4 billion people, are concentrated along or near a coastline (within 250 miles). It is recognized that a mix of energy sources will be required to meet mainstream energy needs of this growing coastal population and bring about the benefits of a diversified energy portfolio. The oceans are teeming with energy, whether it be the more established offshore oil and gas fields or the newer renewable sources such as tidal, wave and offshore wind. This dissertation focused on contributing to the field of offshore geotechnics in two ways: first, to aid in offshore site characterization by developing a framework for correlating soil strength with geophysical measurements for shallow sediments; and second, to study the ultimate capacity of caisson foundations subjected to loads typically encountered in offshore wind tower installations in water depths up to 30 m. The research project describes a laboratory testing program of CKoU triaxial tests along with bender element measurements carried out at Texas A&M University for correlation of soil strength with stiffness. A new framework for correlating stiffness and strength is proposed, based on void ratio and over consolidation ratio (OCR). Although site specific correlations between soil strength and various geophysical measurements is required, the formulation provides a convenient way of estimating both absolute value and trends of behavior at different void ratios and OCRs. This experimental program also allows for the investigation of the small strain response of soils at shallow depths which was previously unstudied. The project also describes a centrifuge testing program carried out at Rensselaer Polytechnic Institute. Model caisson foundations with aspect ratios of two were subjected to combined vertical, horizontal and moment loads usually experienced by offshore wind turbine foundations. This dissertation focuses on the ultimate capacity of the pile response to lateral load, to ensure the foundation has sufficient strength in an extreme loading event

Characterization of Soft Clays and the Response of Soil Foundation Systems for Offshore Applications

The overwhelming bulk of our population, about 4 billion people, are concentrated along or near a coastline (within 250 miles). It is recognized that a mix of energy sources will be required to meet mainstream energy needs of this growing coastal population and bring about the benefits of a diversified energy portfolio. The oceans are teeming with energy, whether it be the more established offshore oil and gas fields or the newer renewable sources such as tidal, wave and offshore wind. This dissertation focused on contributing to the field of offshore geotechnics in two ways: first, to aid in offshore site characterization by developing a framework for correlating soil strength with geophysical measurements for shallow sediments; and second, to study the ultimate capacity of caisson foundations subjected to loads typically encountered in offshore wind tower installations in water depths up to 30 m. The research project describes a laboratory testing program of CKoU triaxial tests along with bender element measurements carried out at Texas A&M University for correlation of soil strength with stiffness. A new framework for correlating stiffness and strength is proposed, based on void ratio and over consolidation ratio (OCR). Although site specific correlations between soil strength and various geophysical measurements is required, the formulation provides a convenient way of estimating both absolute value and trends of behavior at different void ratios and OCRs. This experimental program also allows for the investigation of the small strain response of soils at shallow depths which was previously unstudied. The project also describes a centrifuge testing program carried out at Rensselaer Polytechnic Institute. Model caisson foundations with aspect ratios of two were subjected to combined vertical, horizontal and moment loads usually experienced by offshore wind turbine foundations. This dissertation focuses on the ultimate capacity of the pile response to lateral load, to ensure the foundation has sufficient strength in an extreme loading event

Characterization of Gulf of Mexico Clay Using Automated Triaxial Testing

With increasing development in the oil and gas industry, exploration and production is continuously moving deeper off the continental shelf and onto the continental slopes. This increases the risk of submarine slope failures leading to damage of offshore structures. Thus there is a need to study and understand properties of offshore marine clays on slopes. This study was undertaken in order to understand better the characteristics of a sub-marine clay deposit taken from the Gulf of Mexico. This thesis presents the results of SHANSEP triaxial testing performed on undisturbed samples of Gulf of Mexico clay. Background information is given about the clay, the sampling program and the laboratory testing program. The GEOTAC Truepath automated stress path triaxial apparatus implemented for this research and the laboratory procedures used are described in detail. Data is summarized from the various types of tests run on the clay (CKoU compression and extension, CIU compression and extension tests, consolidations tests) and the stress history of the deposit is evaluated. The SHANSEP reconsolidation technique was used for a comprehensive program of Koconsolidated-undrained (CKoU) triaxial compression and extension tests at overconsolidation ratios (OCR) ranging from one to eight. Eighteen tests were run on jumbo piston core samples from one particular core. The consolidation phase of these SHANSEP tests provided most of the preconsolidation pressure values used to establish the stress history at the two test sites. These tests were used to estimate the in situ Ko and how it varies with OCR. The undrained shear phase of the tests provides detailed information on the values of S and m for use in the SHANSEP undrained strength equation, Su= 0vo = S(OCR)m, effective stress failure envelopes, etc

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

Passive Design Features for Energy-Efficient Residential Buildings in Tropical Climates : The context of Dhaka, Bangladesh

This study aimed at identifying passive design features through extensive literature study that can be incorporated in residential buildings to make them energy efficient. The study also aimed at identifying changes in the design process that can affect energy efficiency in residential buildings. It has analyzed the design features of typical residential buildings representative of upper middle income households in Dhaka through a case study conducted in Dhaka. It also analyzed the present electric energy use for cooling and lighting typical residential buildings of upper middle income households in Dhaka and the possible energy savings by adopting certain energy efficient features in the case study building. It also distinguishes the different roles of developers, architects, interior designers, land owners (clients) and residents that can act as a barrier in achieving energy efficiency in residential buildings. The findings from this study indicate that doubling the thickness of external walls on east and west, use of hollow clay tiles instead of weathering course for roofs and use of appropriate horizontal overhang ratios for all four orientations can reduce the cooling load of the case study building by 64% and hence reduce the total energy use of the building by 26%. Finally it can be concluded that the process of designing energy efficient residential buildings is not a ‘one-man’s show’. Architects, developers, interior designers and clients are the other actors who can bring a change in the design practice.         Keywords: Energy- efficient; passive design features; residential building; tropical climate    

Near-infrared photoactive Cu3BiS3 thin films by co-evaporation

Semiconducting Cu3BiS3 (CBS) thin films were deposited by co-evaporation of Cu, Bi elemental metallic precursors, with in situ sulphurisation, using a quartz effusion cell. Cu3BiS3 thin films were structurally characterized by XRD and FE-SEM. The chemical bonding of the ions was examined by XPS. As deposited films were demonstrated for metal-semiconductor-metal near IR photodectection under lamp and laser illuminations. The photo current amplified to three orders and two orders of magnitude upon the IR lamp and 60 m W cm(-2) 1064 nm IR laser illuminations, respectively. Larger grains, made up of nano needle bunches aided the transport of carriers. Transport properties were explained based on the trap assisted space charge conduction mechanism. Steady state detector parameters like responsivity varied from 1.04 AW(-1) at 60 m Wcm(-2) to 0.22 AW(-1) at 20 m Wcm(-2). Detector sensitivity of 295 was found to be promising and further could be tuned for better responsivity and efficiency in utilization of near infra-red photodetector. (C) 2014 AIP Publishing LLC

Solution Processed Cu2CoSnS4 Thin Films for Photovoltaic Applications

Earth abundant alternative chalcopyrite Cu2CoSnS4 (CCTS) thin films were deposited by a facile sol-gel process onto larger substrates. Temperature dependence of the process control of deposition and desired phase formations was studied in detail. Films were analyzed for complete transformation from amorphous to polycrystalline, with textured structures for stannite phase, as reflected from the X-ray diffraction and with nearly stoichiometric compositions of Cu:Co:Sn:S = 2:0:1:0:1:0:4:0 from EDAX analysis. Morphological investigations revealed that the CCTS films with larger grains, on the order of its thickness, were synthesized at higher temperature of 500 degrees C. The optimal band gap for application in photovoltaics was estimated to be 1.4 eV. Devices with SLG/CCTS/Al geometry were fabricated for real time demonstration of photoconductivity under A.M 1.5 G solar and 1064 rim infrared laser illuminations. A photodetector showed one order current amplification from similar to 1.9 X 10(-6) A in the dark to 2.2 x 10(-5) A and 9.8 X 10(-6) A under A.M 1.5 G illumination and 50 mW cm(-2) IR laser, respectively. Detector sensitivity, responsivity, external quantum efficiency, and gain were estimated as 4.2, 0.12 A/W, 14.74% and 14.77%, respectively, at 50 mW cm(-2) laser illuminations. An ON and OFF ratio of 2.5 proved that CCTS can be considered as a potential absorber in low cost photovoltaics applications

An insight to the low temperature conduction mechanism of c-axis grown Al-doped ZnO, a widely used transparent conducting oxide

Al-doped ZnO thin films were synthesized from oxygen reactive co-sputtering of Al and Zn targets. Explicit doping of Al in the highly c-axis oriented crystalline films of ZnO was manifested in terms of structural optical and electrical properties. Electrical conduction with different extent of Al doping into the crystal lattice of ZnO (AZnO) were characterized by frequency dependent (40 Hz-50 MHz) resistance. From the frequency dependent resistance, the ac conduction of them, and correlations of localized charge particles in the crystalline films were studied. The dc conduction at the low frequency region was found to increase from 8.623 mu A to 1.14 mA for the samples AZnO1 (1 wt% Al) and AZnO2 (2 wt% Al), respectively. For the sample AZnO10 (10 wt% Al) low frequency dc conduction was not found due to the electrode polarization effect. The measure of the correlation length by inverse of threshold frequency (omega(0)) showed that on application of a dc electric field such length decreases and the decrease in correlation parameter(s) indicates that the correlation between potentials wells of charge particles decreases for the unidirectional nature of dc bias. The comparison between the correlation length and the extent of correlation in the doped ZnO could not be made due to the observation of several threshold frequencies at the extent of higher doping. Such threshold frequencies were explained by the population possibility of correlated charge carriers that responded at different frequencies. For AZnO2 (2% Al), the temperature dependent (from 4.5 to 288 K) resistance study showed that the variable range hopping mechanism was the most dominating conduction mechanism at higher temperature whereas at low temperature region it was influenced by the small polaronic hopping conduction mechanism. There was no significant influence found in these mechanisms on applications of 1, 2 and 3 V as biases

Effect of Strontium the phase structure of Ba1−xSrxCe0.65Zr0.2Y0.15O3−δ (0 ≤ x ≤ 0.25) proton conductor by citrate–EDTA complexing sol–gel method

Proton conducting oxides Ba1−xSrxCe0.65Zr0.2Y0.15O3−δ (0 ≤ x ≤ 0.25) are prepared using the citrate–EDTA complexing sol–gel method. The effect of strontium and yttrium doping on the material properties is systematically investigated. The phase formation, thermal analysis, morphology, stability and conductivity measurements are performed on the sintered powders through TG–DTA, XRD, SEM, EDAX, FTIR, Raman and LCR measurements. The results indicated a single-phase orthorhombic system. Strontium incorporation helped in increasing the grain size up to 20% of strontium doping while reducing the lattice parameters and unit cell volume. The ionic conductivities of the Ba1−xSrxCe0.65Zr0.2Y0.15O3−δ sintered oxides increased with increase in the concentration of Sr2+ along with the co-doping strategy of trivalent Y3+ in the B site. Among the synthesized samples, Ba0.8Sr0.2Ce0.65Zr0.2Y0.15O3−δ pellet with orthorhombic structure showed highest conductivity with a value of 2.35 × 10−1 S/cm and 2.41 × 10−1 S/cm at 500 °C due to its smaller lattice volume, larger grain size and lower activation energy that led to excessive increase in conductivity. All pellets exhibited good chemical stability when exposed to air and H2O atmospheres. These results indicate that this composition can be used as a potential electrolyte if synthesis conditions and temperature are well maintained