<p> Ordered Mesoporous Carbons (OMCs) with well-controlled pore structure and narrow pore size distribution demonstrated great potential as highly functional adsorbents. The pore size and surface chemistry of OMCs were considered two of the most important factors that affect the adsorption capacity of organic compounds. The objective of this study is to optimize the structure of OMCs for resorcinol adsorption by changing the pore size and oxygen content using computational approach. New rhombic OMC models with varied pore size and oxygen content were constructed using Materials Visualizer module. The specific surface area, total pore volume, small angle X-ray diffraction patterns, and resorcinol adsorption capacity results were calculated by Forcite and sorption module in Materials Studio package. The simulation results were validated by the experimental data. Experimentally, the OMCs were synthesized using sucrose as carbon precursor by hard-template method. The tunable pore size (4nm to 15nm) and oxygen content of the OMCs are obtained by adjusting the amount of boric acid as a pore-expanding reagent. The experimental results, such as BET surface area, X-ray power diffraction patterns, and adsorption capacity of resorcinol, were compared with the simulation results. The optimal pore size of OMC for resorcinol removal was found to be 6 nm. The simulation results confirmed that oxygen containing functional group was an important factor for adsorption on OMCs. The improvement of adsorption capacity was not so significant comparing with the influence of specific surface area, since the adsorption process was a more of a physical process rather than a process with chemical interaction.</p>

Coastal deltaic floodplains provide an important ecosystem service by removing or retaining nitrate from enriched riverine water. Wetland plants, soils, and microbes within these floodplains use nitrate through uptake, burial, and denitrification, thereby reducing the impact of nitrate on algal blooms and hypoxia in the Gulf of Mexico. However, these processes depend on the physical, biological, and chemical conditions within the floodplain. Understanding and characterizing the hydrodynamics of these systems and the relative impact of river, tide, and wind forcings are the first steps in understanding the biogeochemical processes controlling nitrate removal. Motivated by the desire to identify biogeochemical hotspots within coastal deltaic floodplains, this project focuses on modeling the hydrodynamics of these complex wetland ecosystems. Biogeochemical hotspots occur where anaerobic soils, sufficient organic carbon supply, longer residence times, and warmer water temperatures create optimal conditions for processes such as denitrification. The latter two conditions are strongly controlled by the hydrodynamics of the system. A Delft3D-FLOW model is developed for Wax Lake Delta, an actively prograding delta in southeastern Louisiana, in order to simulate daily and seasonal changes in water temperature and residence time within different hydrogeomoprhic zones of coastal deltaic floodplains. From January to March 2015, intertidal floodplains have warmer temperatures and longer residence times (up to 2.5 days) than subtidal floodplains (up to 1.5 days). However, when river discharge increases during spring floods, connectivity between channels and floodplains increases and residence times within all zones decreases as water is flushed more quickly to the Gulf of Mexico. Correctly simulating residence time of water within floodplains is essential to future efforts to model the transformation of nitrate in these systems.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Also issued in pages. / Includes bibliographical references (leaves 124-125). / The People's Republic of China (PRC) has the world's fastest growing economy, with further growth currently depending on improvement of physical infrastructure. As it enters what many predict to be one of the greatest infrastructure development booms in history, China presents numerous opportunities to international engineering, procurement and construction firms. The PRC has recognized that further economic growth depends on improved infrastructure, but it is short on cash. In order to finance and build much of the infrastructure required for continued economic growth, the Chinese government is looking to use the Build-Operate-Transfer (BOT) approach, taking advantage of the interest of foreign investors to meet China's huge infrastructure needs. As a result, while there are many tenders for conventional construction contracts, there are even greater opportunities (and potentially higher margins) for foreign firms that can supply the capital to fund construction as well as the technology and management skills to build and operate infrastructure facilities. However, there are strings attached. The potential benefits of participating in the Chinese infrastructure boom are accompanied by correspondingly large risks. With an economy in the midst of a transition from controlled to open market, politics mired in bureaucracy and corruption, and a legal system offering little enforceability of contracts, China presents some extraordinary problems for foreign construction firms hoping to participate in the BOT boom. China is not an easy place to do business. In fact, BOT projects in the PRC are fraught with risks, from currency convertibility and inflation to government approval problems and the lack of a reliable legal system. This paper looks at the growing infrastructure demand in China and how both China and foreign companies can benefit from working together to tackle that demand. The paper first outlines the extent of opportunities for international EPC firms in China. Next, it identifies the risks that must be considered before participating in Chinese infrastructure Build-Operate-Transfer concessions. Finally, the paper will examine methods by which international constriction firm's can mitigate these risks and maximize its benefits in the Chinese BOT boom. / by Melissa Wen Dan Huang. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references (leaves 74-75). / The fast-tracking delivery method has received considerable attention in recent years. Its time saving feature has placed it as an alternative to the sequential method. Effective fast-tracking may shorten delivery time and lower project costs. However, it should be highlighted that fast tracking also inherits a greater potential for an unexpected cost increase due to uncertainty in planning and management. To handle such inherent risks, fast-tracking should be undertaken with proper planning and management in a systematic manner. A closer observation of the design and construction process reveals that all of the cost-increasing factors in fast-tracking are directly or indirectly related to non value-adding or corrective changes. These changes are mainly attributed to uncertainty that is rooted in the interdependency of project tasks. Consequently, reducing this interdependency and managing the undesirable interactions among project tasks hold a key to successful fast-tracking. To meet these challenges, a robust planning and control methodology is developed to provide a systematic solution. The proposed methodology is elaborated based on concurrent engineering and system dynamics. Concurrent engineering is applied to develop an overlapping framework for the construction processes and to enable the interdependency among them to be minimized. The system dynamics modeling approach helps analyze and quantify the effect of dynamic interactions among the design and construction processes. The final result of this research may help ensure that the fast-tracking approach achieves sizable delivery time reductions without driving up costs. The provision of an optimal overlapping strategy, workforce control policy, and schedule adjustments assists in satisfying this goal. / by Moonseo Park. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references (p. 263). / Large vertical (axial) and lateral loads often act on the heads of drilled shafts in jointed rock. In current design practice, the p-y curve method used in design of laterally loaded drilled shafts in soil is adopted in the design of such shafts in jointed rock. The p-y curve method treats the soil as a continuum. The continuum model is not applicable to jointed rock, in which the joints form blocks. A new discontinuum model was developed in this thesis to determine the lateral load capacity of drilled shafts in a jointed rock mass with two and three joint sets. It contains two parts: a kinematic and a kinetic analysis. In the kinematic analysis, the removability theorem of a convex block is expanded to analyze the removability of a block intersecting a pile and the removability of a combination of blocks. Based on these removability theorems, a method was developed to select removable combinations of blocks using easily constructed 2-dimensional figures only. In kinetics, each selected removable combination of blocks is analyzed with the limit equilibrium approach to determine the ultimate lateral load capacity. Although the analysis is similar to slope stability analysis, it is more complicated with the addition of a lateral force exerted by the pile and the vertical pile load exerted on the wedge. The analysis also considers the weight of the wedge, the shearing resistance along the joints, and the vertical pile load exerted on the wedge. Simple analytical relations were developed to solve for the ultimate lateral load capacity. / by Albert C. To. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references (p. 151-155). / The intent of this thesis is to propose a framework for strategic thinking in the global market for large-scale Japanese construction firms. That framework would enable firms to perform strategic thinking in a changing environment, capturing dynamic aspects of the industry and lead them to succeeding processes toward their choice of strategic position. The thesis first reviews literature on strategic thinking and finds three distinct powerful strategic analysis models, which together cover virtually all of the major important theories in strategic management. These three models are the Porter Model, the Resource-Based View of the Firm, and the Delta Model. The thesis then reviews the three models, examining their applicability to the industry, and analyzes their strengths and weaknesses. Based on this analysis, the thesis integrates them and proposes the new framework, which consists of two contiguous approaches, the iterative and the circular dynamic. Finally, the thesis applies the framework to a Japanese construction firm through some case studies, which allows this thesis to depict practical usage of the proposed framework as well as prove its applicability to the global construction market. This application further develops and complements the framework. / by Satoshi Suzuki. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references (leaves 90-95). / In this thesis, we propose a methodology for incorporating attitudinal data in a choice model to capture unobservable heterogeneity across the population. The key features of this approach are, 1) the concept of latent attitudes, and the assumption that 2) the respondent's answers to psychometric attitudinal questions relating to the importance of attributes are manifestations of these attitudes and that 3) those attitudinal data bring sufficient information to capture unobservable heterogeneity across the population in the context of choice behavior. Each individual is probabilistically assigned to a finite number of segments according to his/her own value of latent attitudinal variable(s) as well as to threshold parameter(s) common to the population. Segment-specific parameters are estimated simultaneously. An empirical case study on shopping trip mode choice demonstrates the effectiveness of the methodology. / by Takamichi Hosoda. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references (leaves 69-70). / This thesis examines the opportunities created by information technology for individuals at the executive level in the engineering and construction industry, in particular with respect to networking and interaction. The foundations of this research emerge in part from a project initiated by the World Economic Forum in the late 1980s aimed at connecting its members, executives of global companies, through a virtual network. The project was called Welcom for World Electronic Community, and it was a first attempt in developing an information technology solution focused on executive's needs. To understand how information technology today, primarily through the Internet and the web, can be utilized at the executive level, it is critical to analyze these needs. This analysis is done in this thesis via a survey of about 20 executives from the engineering and construction industry. The survey is based on a series of interviews, followed by a questionnaire. The interviews reveal critical tasks for executives such as interacting and networking with clients and peers. How information technology is used to add value to these tasks and in particular the aspects of virtual versus face to face interaction is examined. The questionnaire acts as a follow-up to the interviews and reveals the interest of using the web as a content provider to executives for issues such as industry specific economic and financial information. The thesis combines literature research on the information technology revolution, the analysis of the Welcom initiative, and the survey. This provides us with insight about how information technology is having an influence on the way executives in the engineering and construction industry interact, communicate and do business today, and the potential opportunities for the future. / by Olivier M. Schwab. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references (leaves 90-92). / In large-scale projects, collaboration is an essential key for the success of projects. Since different participants from different organizations try to work together in projects, competitive stresses exist in their relationships and as a result, disputes or conflicts may inevitably occur. Pena-Mora and Wang (1998) have developed a preliminary collaborative negotiation methodology for facilitating/mediating the negotiation process of conflicts. In order for that collaborative negotiation methodology to be more detailed for its implementation, it needs to account for the effect of project structure and delivery method on the negotiation processes in large-scale projects. Because contracts define the temporary formal and informal relationships among the different parties in a project and subsequently, they define the framework of the negotiations of conflicts within that project, different delivery systems may be more or less effective in terms of conflict resolution. In this research, to study the effect of delivery system on negotiation of conflicts, first, several different project structures and delivery systems are studied in order to identify participants' roles, responsibilities, and relationships. Second, potential conflicts in relationships among project participants are examined to show that each delivery system has typical or pattern behavior that may affect the interrelationship among groups on negotiations. These patterns or characteristics of the groups and their relationship make possible to evaluate quantitatively and qualitatively the advantage or disadvantage of each delivery system in terms of conflict avoidance or dispute resolution. Then, indexes of negotiation effectiveness for each delivery system are developed in order to quantify the advantage of implementing the collaborative negotiation methodology in a large-scale project within a particular delivery system. / by Tadatsugu Tamaki. / S.M.

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references (v. 2, leaves 411-427). / This thesis presents theoretical predictions and experimental validation of a newly designed tapered piezoprobe penetrometer that is currently being used in offshore site investigation. The new device measures pore pressures at the tip of a 1/4" diameter extension piece that connects through a tapered section to conventional drill rods. By accelerating the dissipation of penetration-induced excess pore pressures, the design aims to provide reliable measurements of in situ pore pressures in low permeability marine clays in a much shorter timeframe than is possible with conventional piezocone devices. Predictions of probe performance are obtained using a non-linear coupled consolidation analysis, in which the effective stress-strain properties of the soil are characterized by the MIT-E3 model, and the initial penetration process is simulated using the Strain Path Method. The predictions show that the dissipation response can be divided into three stages: I) initial dissipation that is controlled by the radius of the extension piece; II) a transition stage, characterized by marked retardation of dissipation response, due to migration of pore water generated around the shaft of the drill rods; and III) long term response that converges to the behavior of a conventional piezocone and is not affected by the presence of the tip extension piece. Parametric studies show that the pore pressure dissipation is affected by the stress history of the clay and it's anisotropic flow properties, as well as details of the probe geometry. Although the design can be improved by increasing the length of the extension piece, the most useful modification of the design is to add a second pore pressure sensor located above the taper section on the driB shaft. Data from this designed dual sensor piezoprobe can then be interpreted using two new methods proposed in this thesis: I) Two-point intersection method that correlates the dissipated pore pressures at the two sensor locations in order to estimate the in situ pore pressures, u0, from an incomplete dissipation record. 2) Concurrent matching of dissipation data at the two monitoring points can be used to define the in-sim hydraulic conductivity. The theoretical predictions are evaluated through detailed comparisons with field dissipation measurements for piezoprobe and piezocone devices at MIT test site in Saugus, Massachusetts. In general, there is excellent agreement between the predicted and measured pore pressure dissipation for test performer at depths 65-1 15 ft. The backfigured hydraulic conductivities are consistently lower than laboratory measurements by approximately a factor of two. However, the in-situ pore pressure, u0 , can be estimated with 5% accuracy within I hr from the start of the dissipation test. Pore pressure dissipation is directly related to time dependent increases in the capacity of driven piles. Predictions of this set-up behavior are obtained by simulating the effective stress changes that occur in the soil close to the pile shaft during installation, coupled consolidation and undrained axial pile loading. Parametric studies establish the effects of stress history, pile geometry (radius and wall thickness) on predictions of the time dependent pile set-up. There is a significant difference in behavior predicted for sensitive, low plasticity clays and insensitive plastic clays. Site specific predictions are evaluated through comparisons with field data from instrumented model piles at four well-documented test sites. A generic design methodology is proposed for interpreting dissipation data from the tapered piezoprobe and predicting pile set-up at deepwater sites in the Gulf of Mexico. The proposed design charts are based on synthesized soil properties for an Average Gulf Clay. Preliminary calculations for pile load tests performed at the West Delta site confirm the importance of reliable measurements of in situ pore water pressures and soil pre-consolidation pressures. / by Twarath Sutabutr. / Sc.D.