On the implicit immersed boundary method in coupled discrete element and lattice Boltzmann method

The coupled discrete element method and lattice Boltzmann method (DEMLBM) has increasingly drawn attention of researchers in geomechanics due to its mesoscopic nature since 2000. Immersed boundary method (IBM) and immersed moving boundary (IMB) are two popular schemes for coupling fluid particle in DEMLBM. This work aims at coupling DEM and LBM using the latest IBM algorithm and investigating its accuracy, computational efficiency, and applicability. Two benchmark tests, interstitial fluid flow in an ideal packing and single particle sedimentation in viscous fluid, are carried out to demonstrate the accuracy of IBM through semi‐empirical Ergun equation, finite element method (FEM), and IMB. Then, simulations of particle migration with relatively large velocity in Poiseuille flow are utilized to address limitations of IBM in DEMLBM modeling. In addition, advantages and deficiencies of IBM are discussed and compared with IMB. It is found that the accuracy of IBM can be only guaranteed when sufficient boundary points are used and it is not suitable for geomechanical problems involving large fluid or particle velocity

The role of web-based promotion on the development of a relationship marketing model to enable sustainable growth

AbstractIn recent years the web-based Relationship Marketing (RM) has been receiving a great attention from e-marketing perspective. The RM is evolved as a contemporary marketing initiative, which can be applied to all types of industries. Concurrently, because of the advancement of the Information Technology, web-based promotion and market offering are considered as dominating business development tool. From this context, five grown sporting cases have been analysed to realise how web-based promotion influences RM to develop a sustainable growth model, where the cases have been utilising the RM and web-based promotion lucratively to attain and retain the key stakeholders to sustain their growth. Following the initial literature review, the websites of the cases have been scrutinised thoroughly as data collection tool. Nineteen RM indicators are identified as different RM perspectives. The cases are positioning web-based promotions and offerings underlying these RM indicators as a combined promotional effort to enhance competitive advantage. From the case analysis, the concept of stakeholder causal scope is evolved as identical with this combined promotional effort, as well as proportionate with at least one of the four identified growth strategies. Finally, the RM centred ‘Sustainable Growth Model’ has been developed through the synthesis of the impact of the web-based RM indicator focused combined promotional effort of the cases on the associated stakeholder causal scopes and their relevancy with the growth strategies. Reinforcing the model is established significantly for marketers in various industries to enhance competitive advantage aiming to sustain organisational growth

Dewatering of a Large Excavation Pit by Wellpoints

An excavation, rectangular in dimensions of 55 m x 95 m at the base and approximately 120 m x 160 m at the ground surface was made possible by the use of multi-staged wellpoint dewatering system. Groundwater table was lowered more than 20 meters using four stage wellpoint system to construct the main wastewater pump station for the city of Izmir. The most significant soil parameter affecting the planning and design of the dewatering work is the coefficient of field permeability, and it has been directly measured by a large scale pumping test at the site. During dewatering and construction stages, piezometers, inclinometers, extensometers and both conventional surveying and EDM methods were used. Total discharge rate was measured at different stages and it is compared with the theoretical approaches. Partial penetration factor for the well into aquifer is estimated

Stress intensity factor estimation of repaired aluminum plate with bonded composite patch by combined genetic algorithms and FEM under temperature effects

The finite element method (FEM) is used to analyze the behavior of repaired cracks in 2024-T3 aluminum with bonded patches made of unidirectional composite plates. Different plate thicknesses, number of patch layers, temperatures and crack lengths are considered in the analyses. Firstly, the KI stress intensity factor (SIF) is calculated by the finite element method using displacement correlation technique. Secondly, non-linear estimation models are developed using genetic algorithms (GA). The developed models are validated with experimental and numerical data. A genetic algorithm patch design (GAPD) is developed to estimate the stress intensity factor without any further finite element analysis

SPH based numerical treatment of the interfacial interaction of flow with porous media

In this paper, the macroscopic equations of mass and momentum are developed and discretised based on the Smoothed Particle Hydrodynamics (SPH) formulation for the interaction at an interface of flow with porous media. The theoretical background of flow through porous media is investigated in order to highlight the key constraints which should be satisfied, particularly at the interface between the porous media flow and the overlying free flow. The study aims to investigate the derivation of the porous flow equations, computation of the porosity, and treatment of the interfacial boundary layer. It addresses weak assumptions that are commonly adopted for interfacial flow simulation in particle‐based methods. As support to the theoretical analysis, a 2D weakly compressible SPH (WCSPH) model is developed based on the proposed interfacial treatment. The equations in this model are written in terms of the intrinsic averages and in the Lagrangian form. The effect of particle volume change due to the spatial change of porosity is taken into account and the extra stress terms in the momentum equation are approximated by using Ergun's equation and the Sub‐Particle Scale (SPS) model to represent the drag and turbulence effects, respectively. Four benchmark test cases covering a range of flow scenarios are simulated to examine the influence of the porous boundary on the internal, interface and external flow. The capacity of the modified SPH model to predict velocity distributions and water surface behaviour is fully examined with a focus on the flow conditions at the interfacial boundary between the overlying free flow and the underlying porous media

Antimicrobial Activity of Flavonoids against Extended-Spectrum &#946-Lactamase (ES&#946L)-Producing Klebsiella pneumoniae

Purpose: In the present study, six flavonoids (5,7-dimethoxyflavanone-4'-O-&#946-D-glucopyranoside, 5,7- dimethoxyflavanone-4'-O-[2''-O-(5'''-O-trans-cinnamoyl)-&#946-D-apiofuranosyl]-&#946-D-glucopyranoside, naringenin-7-O-&#946-D-glucopyranoside, 5,7,3'-trihydroxy-flavanone-4'-O-&#946-D-glucopyranoside, rutin, and nicotiflorin) isolated from Galium fissurense, Viscum album ssp. album and Cirsium hypoleucum were screened against extended-spectrum &#946-lactamase producing multidrug-resistant (trimetoprimesulphametoxazole, sulbactam-ampicillin, clavulonate-amoxicilin, ceftriaxon, cefepime, imipenem, ceftazidime, tobramicin, gentamicin, ofloxacin, ciprofloxacin) bacteria Klebsiella pneumoniae (ES&#946Ls). Methods: We performed susceptibility testing according to the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) and used an inhibition endpoint for determination of the minimum inhibition concentrations (MICs). Results: All the flavonoids showed in vitro antimicrobial activity against all the isolated strains of K. pneumoniae similar to the control antibacterial (ofloxacin) at the concentrations of 32 - 64 μg ml-l; another control, ampicillin, had no activity. Since, ES&#946L-producing strains are known to be resistant to all &#946-lactam antibiotics, our results fall notably within the concentration range for antimicrobial activity. Conclusion: To the best of our knowledge, this is the first report of the study of the activity of these flavonoids against (ES&#946L)-producing K. pneumoniae and may throw light to the low-toxicity of flavonoids, and their potentials for developing therapies for infections caused by ES&#946L-producing bacteria in the future. Further work is under investigation to identify their precise antibacterial mechanism. Keywords: Antimicrobial activity, ES&#946Ls, Flavonoids, Klebsiella pneumoniae, Ofloxacin, Ampicillin.Tropical Journal of Pharmaceutical Research Vol. 7(4) 2008: pp. 1151-115

A new detection method for capacitive micromachined ultrasonic transducers

Cataloged from PDF version of article.Capacitive micromachined ultrasonic transducers (cMUT) have become an alternative to piezoelectric transducers in the past few years. They consist of many small circular membranes that are connected in parallel. In this work, we report; a new detection method for cMUTs. We model the membranes as capacitors and the interconnections between the membranes as inductors. This kind of LC net-work is called an artificial transmission line. The vibrations of the membranes modulate the electrical length of the transmission line, which is proportional to the frequency of the signal through it. By measuring the electrical length of the artificial line at a high RF frequency (in the gigahertz range), the vibrations of the membranes can be detected in a very sensitive manner. Far the devices we measured, we calculated the minimum detectable displacement to be in the order of 10(-5) Angstrom/root Hz with a possible improvement to 10(-7) Angstrom/root Hz