Simplified homogenization method in stone column designs

AbstractThe homogenization technique has been developed to model stone column improved grounds by establishing the equivalent material properties for the composite ground. However, homogenization techniques based on the elasto-plastic behavior of the constituent materials found in literature require modification in terms of the finite element constitutive models which are difficult for practical engineers to apply. Therefore, a simple yet effective way of predicting the consolidation performance of stone column improved grounds has been invoked in this study. The method is called the equivalent column method (ECM). The new method provides not only equivalent stiffness for the composite material, but also equivalent permeability. The method is derived from an analysis using the unit cell model in a 2D finite element axisymmetrical model. The settlement is calculated and a correction factor is obtained via a comparison with the results calculated using a single averaging composite stiffness for the improved ground. Correlations are summarized in the form of design charts for the key parameters, such as the area replacement ratio, the loading intensity, and the friction angle of the column material. Through a series of tests for different area replacement ratios, the equivalent permeability is established and presented in a design chart for different permeability ratios. ECM shows a good agreement with the current design methods and field results. The advantage of the proposed method over other homogenization techniques is the simplicity of its use which renders easy model set-up in the finite element program, especially for embankments and large tank problems, besides its extra ability to predict the consolidation time

Removal of Zinc by the Moss Calymperes delessertii Besch

Studies were conducted to assess the capability of a moss, Calymperes delessertii Besch, to remove zinc from solutions. In the batch experiments, parameters studied included effect of pH and initial zinc concentration on sorption. A series of fixed bed experiments were performed to study the system under dynamic conditions. The bed depth service time (BDST) model proposedn by Hutchins was successfully applied to the system. The fixed bed experiments were also carried out using waste water from a zinc plating factory and results indicated that moss columns could be used in a clean-up system to remove zinc from electroplating waste water

C‐reactive protein level as a predictor of difficult emergency laparoscopic cholecystectomy

Background: Studies focused on C‐reactive protein (CRP) as a marker of difficult laparoscopic cholecystectomy are limited to small case series. The aim of this study was to evaluate the association between preoperative CRP concentration and difficulty of laparoscopic cholecystectomy in patients admitted with a biliary emergency presentation. Methods: Patients with an emergency admission for biliary disease treated between 2012 and 2017 with a documented preoperative CRP level were analysed. Elective patients and those with other concurrent causes of increased CRP concentration were excluded. The intraoperative difficulty grade was based on the Nassar scale. Statistical analysis was conducted to determine the association of preoperative CRP level with difficulty grading, adjusted for the interval to surgery. Results: A total of 804 emergency patients were included. The mean preoperative peak CRP level was 64·7 mg/l for operative difficulty grade I, 69·6 mg/l for grade II, 98·2 mg/l for grade III, 217·5 mg/l for grade IV and 193·1 mg/l for grade V, indicating a significant association between CRP concentration and Nassar grade (P < 0·001). Receiver operating characteristic (ROC) curve analysis showed an area under the curve of 0·78 (95 per cent c.i. 0·75 to 0·82), differentiating patients with grade I–III from those with grade IV–V operative difficulty. ROC curve analysis found a cut‐off CRP value of 90 mg/l, with 71·5 per cent sensitivity and 70·5 per cent specificity in predicting operative difficulty of grade IV or V. Logistic regression analysis found preoperative peak CRP level to be predictive of Nassar grade I–III versus grade IV–V operative difficulty, also when adjusted for timing of surgery (odds ratio 5·90, 95 per cent c.i. 2·80 to 12·50). Conclusion: Raised preoperative CRP levels are associated with greater operative difficulty based on Nassar scale grading

The Impact of Electronic Customer Relationship Management (e-CRM) on the Business Performance of Small Company

Small company has a relatively simple e-CRM to improve their customer relationships and information gathering management to create competitive advantage.The use of e-CRM for small company is in a different context as compared to that for the large company. The technology acceptance model was used to investigate the relationship of perceived usage of e-CRM with business performance of all the identified seventy-one (71) small companies that sell cars at Batu Pahat town. Relationship marketing principles have seldom been applied to the small and medium-sized enterprise (SME). Mean test and multiple regression were used to examine internet CRM and business performance

On the Precision of a Length Measurement

We show that quantum mechanics and general relativity imply the existence of a minimal length. To be more precise, we show that no operational device subject to quantum mechanics, general relativity and causality could exclude the discreteness of spacetime on lengths shorter than the Planck length. We then consider the fundamental limit coming from quantum mechanics, general relativity and causality on the precision of the measurement of a length.Comment: 5 pages, to appear in the proceedings of the 2006 International School of Subnuclear Physics in Erice and in ''Young Scientists'' online-only supplement of the European Physical Journal C-Direct (Springer

Phenomenological Consequences of Singlet Neutrinos

In this paper, we study the phenomenology of right-handed neutrino isosinglets. We consider the general situation where the neutrino masses are not necessarily given by $m_D^2/M$, where $m_D$ and $M$ are the Dirac and Majorana mass terms respectively. The consequent mixing between the light and heavy neutrinos is then not suppressed, and we treat it as an independent parameter in the analysis. It turns out that $\mu-e$ conversion is an important experiment in placing limits on the heavy mass scale ($M$) and the mixing. Mixings among light neutrinos are constrained by neutrinoless double beta decay, as well as by solar and atmospheric neutrino experiments. Detailed one-loop calculations for lepton number violating vertices are provided.Comment: Revtex file,TRI-PP-94-1,VPI-IHEP-94-1, 23 pages, a compressed for 8 figures is appende

Finite-temperature Fermi-edge singularity in tunneling studied using random telegraph signals

We show that random telegraph signals in metal-oxide-silicon transistors at millikelvin temperatures provide a powerful means of investigating tunneling between a two-dimensional electron gas and a single defect state. The tunneling rate shows a peak when the defect level lines up with the Fermi energy, in excellent agreement with theory of the Fermi-edge singularity at finite temperature. This theory also indicates that defect levels are the origin of the dissipative two-state systems observed previously in similar devices.Comment: 5 pages, REVTEX, 3 postscript figures included with epsfi

High performance liquid chromatography (HPLC) analysis for flavonoids profiling of Napier grass herbal tea

Natural plant products are becoming more and more essential in helping to promote safe well-being worldwide. This leads to a substantial rise in the consumption of various herbal teas. The presence of beneficial bioactive ingredients such as flavonoids may be correlated with Napier grass herbal tea having health benefits associated with their intake. Studies have shown that herbal teas have preferentially high antioxidant activity due to the presence of flavonoids in them. The purpose of this study was to identify the Napier grass herbal teas flavonoids prepared under different conditions. Napier grass herbal teas have been formulated using green tea and black tea processes, respectively. The tea samples were extracted in water (95°C, 30 mins) and 60% (v/v) aqueous methanol (30 mins), respectively. Approximately, 1% (v/v) aqueous acetic acid solution (solvent A) and acetonitrile (solvent B) were used as the mobile phase. The flow rate was adjusted to 0.7 mL/min, the column was thermostatically controlled at 28°C, and the injection column was kept at 20 μL. HPLC chromatograms were detected using a photodiode array UV detector at 272 nm. Gallic acid, P-coumaric acid, catechin, epigallocatechin gallate, quercetin, rutin, myricetin and kaempferol were found in both Napier grass water and methanolic extracts, respectively. The findings suggested that the HPLC techniques are ideal for the detection and identification of flavonoids in Napier grass teas