scholarly journals Recent development in biogeotechnology and its engineering applications

2021 ◽  
Author(s):  
Hanjiang Lai ◽  
Shifan Wu ◽  
Mingjuan Cui ◽  
Jian Chu
Keyword(s):  
Geotechnical Engineering ◽  
Soil Improvement ◽  
Model Tests ◽  
Engineering Applications ◽  
Scaled Model ◽  
Proper Understanding ◽  
Factors Affecting ◽  
Pilot Trials ◽  
Potential Applications ◽  
Similarities And Differences

AbstractMicrobial geotechnology or biogeotechnology is a new branch of geotechnical engineering. It involves the use of microbiology for traditional geotechnical applications. Many new innovative soil improvement methods have been developed in recent years based on this approach. A proper understanding of the various approaches and the performances of different methods can help researchers and engineers to develop the most appropriate geotechnical solutions. At present, most of the methods can be categorized into three major types, biocementation, bioclogging, and biogas desaturation. Similarities and differences of different approaches and their potential applications are reviewed. Factors affecting the different processes are also discussed. Examples of up-scaled model tests and pilot trials are presented to show the emerging applications. The challenges and problems of biogeotechnology are also discussed.

scholarly journals Effect of Silica Fume as a Waste Material for Sustainable Environment on the Stabilization and Dynamic Behavior of Dispersive Soil

2021 ◽  
Vol 13 (8) ◽  
pp. 4321
Author(s):  
Murat Türköz ◽  
Seyfettin Umut Umu ◽  
Ogan Öztürk
Keyword(s):  
Silica Fume ◽  
Dynamic Properties ◽  
Soil Improvement ◽  
Waste Material ◽  
Resonant Column ◽  
Engineering Applications ◽  
Positive Effects ◽  
Sustainable Environment ◽  
Earthen Dams ◽  
Dispersive Soils

The use of dispersive soils, which are common in many parts of the world, in engineering applications such as water structures, earthen dams and road embankments is possible with their improvement. Recently, the effects of different chemicals on the stabilization of dispersive soils have been investigated. The use of waste materials in stabilization is preferred both because of the more sustainable environment and the economic advantages it provides. The use of silica fume (SF) as a waste material in different engineering applications provides an important advantage in environmentally and economically sustainable ways. Many studies have been carried out regarding silica fume, especially in the construction industry. Although SF is used in many industries, there is no study about its potential impact on the stabilization and dynamic properties of dispersive soils. In this study, first, Atterberg limits and standard Proctor compaction tests were performed on the mixtures prepared by adding different SF percentages (0, 5, 10, 15, 20, 25 and 30%). Afterward, pinhole tests and resonant column tests were performed to determine dispersibility and dynamic properties on the samples prepared by compaction characteristics for each SF percentage reached. In general, it was determined that SF contributed to a change in soil class, and improvement in dispersibility and dynamic properties of the soil sample, depending on SF content; positive effects of SF were observed in terms of shallow soil improvement.

Guidelines for CFD Simulations of Spar VIM

2013 ◽  
Author(s):  
Charles Lefevre ◽  
Yiannis Constantinides ◽  
Jang Whan Kim ◽  
Mike Henneke ◽  
Robert Gordon ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Test Data ◽  
Model Test ◽  
Model Tests ◽  
Full Scale ◽  
Mooring System ◽  
Time Step ◽  
Cfd Simulations ◽  
Scaled Model ◽  
Sway Motion

Vortex-Induced Motion (VIM), which occurs as a consequence of exposure to strong current such as Loop Current eddies in the Gulf of Mexico, is one of the critical factors in the design of the mooring and riser systems for deepwater offshore structures such as Spars and multi-column Deep Draft Floaters (DDFs). The VIM response can have a significant impact on the fatigue life of mooring and riser components. In particular, Steel Catenary Risers (SCRs) suspended from the floater can be sensitive to VIM-induced fatigue at their mudline touchdown points. Industry currently relies on scaled model testing to determine VIM for design. However, scaled model tests are limited in their ability to represent VIM for the full scale structure since they are generally not able to represent the full scale Reynolds number and also cannot fully represent waves effects, nonlinear mooring system behavior or sheared and unsteady currents. The use of Computational Fluid Dynamics (CFD) to simulate VIM can more realistically represent the full scale Reynolds number, waves effects, mooring system, and ocean currents than scaled physical model tests. This paper describes a set of VIM CFD simulations for a Spar hard tank with appurtenances and their comparison against a high quality scaled model test. The test data showed considerable sensitivity to heading angle relative to the incident flow as well as to reduced velocity. The simulated VIM-induced sway motion was compared against the model test data for different reduced velocities (Vm) and Spar headings. Agreement between CFD and model test VIM-induced sway motion was within 9% over the full range of Vm and headings. Use of the Improved Delayed Detached Eddy Simulation (IDDES, Shur et al 2008) turbulence model gives the best agreement with the model test measurements. Guidelines are provided for meshing and time step/solver setting selection.

scholarly journals Geotechnical engineering behaviors of gellan gum biopolymer treated sand

2016 ◽  
Vol 53 (10) ◽  
pp. 1658-1670 ◽  
Author(s):  
Ilhan Chang ◽  
Jooyoung Im ◽  
Gye-Chun Cho
Keyword(s):  
Geotechnical Engineering ◽  
Friction Angle ◽  
Soil Improvement ◽  
Gellan Gum ◽  
Strengthening Effect ◽  
Calcite Precipitation ◽  
Unconfined Compression Test ◽  
Sand Particles ◽  
Engineering Practices ◽  
Moisture Conditions

Biological approaches have recently been explored as environmentally friendly alternatives to engineered soil methods in geotechnical engineering practices. The use of microbial induced calcite precipitation, reactive enzymes, and microbial polymers, such as biopolymers, in soil improvement has been studied by researchers around the world. In the present study, gellan gum, a microbial polysaccharide generally used in the food industry due to its hydrogel rheology, was used to strengthen sand. The effects of gellan gum on the geotechnical behaviors of cohesionless sand were evaluated through a series of experimental programs including an unconfined compression test, direct shear test, falling head permeability test, and scanning electron microscopy. The geotechnical properties (friction angle, cohesion, and unconfined compressive strength) of gellan gum–treated sands were determined based on varying moisture conditions: initial, dried, and re-submerged. Gellan gum has a distinct strengthening effect on cohesionless sands through artificial cohesion that varies with the moisture conditions. The strengthening effect of gellan gum on sand appears to be a result of the combination of enhanced bonding between unreactive sand particles and the agglomeration of sand particles through hydrogel condensation, in which the agglomerated sand particles behave as enlarged aggregates in soil.

scholarly journals Towards Developing Innovation Management Framework (IMF) for ICT Organizations at Pakistan

2021 ◽  
Author(s):  
Eram Abbasi ◽  
Imran Amin ◽  
Shama Siddiqui
Keyword(s):  
Comparative Analysis ◽  
Literature Review ◽  
Innovation Management ◽  
Factors Affecting ◽  
Management Framework ◽  
Underdeveloped Countries ◽  
The Past ◽  
Similarities And Differences ◽  
Industry Culture ◽  
Developed World

Abstract Various aspects of innovation management have been discussed in literature over the past few decades. Most of the innovation management frameworks have been formulated by undertaking studies in the developed world and lack the industry / culture specific focus. In this paper we revisit the generic innovation management studies to develop an innovation management framework for highlighting the factors affecting innovation specifically at the ICT sector of Pakistan. A detailed literature review has been conducted to identify the factors included in the past innovation management models. To identify the factors specific for Pakistan, senior level professionals, working at the Pakistani ICT organizations were interviewed. A comparative analysis of the innovation management frameworks for Pakistan against those previously found in literature revealed interesting similarities and differences. Based on the study findings, an innovation management framework is developed that highlights the present factors which are important for innovation in the ICT sector for Pakistan. This framework can be used by Pakistan and other underdeveloped countries for improving their innovation in ICT sectors in particular and other sectors in general.

scholarly journals Caracterización ficológica en manantiales de la cuenca baja del sistema hidrológico del Pánuco, México

2017 ◽  
pp. 21 ◽  
Author(s):  
Javier Carmona-Jiménez ◽  
Gustavo Montejano-Zurita
Keyword(s):  
Environmental Factors ◽  
Light Intensity ◽  
Current Velocity ◽  
Growth Forms ◽  
Factors Affecting ◽  
Similarities And Differences ◽  
The Relationship

The results of a phycofloristic study on three springs in the Huasteca Potosina region are presented; 67 species are reported. Floristic similarities and differences among the springsare analized, as well as the relationship between species and environmental factors. Microhabitas were defined in the springs as well as the principal algal asociations that characterize them. Light intensity and current velocity are the most important factors affecting the predominant growth forms present in this type of habitat.

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