Soil-Pile Interaction Analysis using FE-BE Coupling in Frequency Domain

In this study, a numerical method for soil-pile interaction problems in multi-layered half-plane is developed in frequency domain using FE-BE coupling technique. The soil-pile interaction system is divided into two parts, so-called near field and far field. In the near field, beam elements are used for modeling pile and plane-strain finite elements for surrounding soil media. Also, a superstructure is considered as a lumped mass on a pile. In the far field, layered soil media is modeled by boundary element formulation using the dynamic fundamental solution. Then, these two fields are assembled using FE-BE coupling technique. This coupled numerical method automatically satisfies the radiation conditions because the far field boundary element formulation can handle the radiation conditions in a half plane. Additionally, the difference of relative displacement at the interface between soil and pile is considered by applying interface spring elements. In order to verify the proposed method for soil-pile interaction system, the dynamic responses of a pile in a multi-layered half-plane are performed and the numerical results are compared with the measured values from experiments. It is shown that the developed method can be an efficient numerical tool to solve the dynamic response of a pile buried in a multi-layered half plane

Bladder Reconstruction Using Bovine Pericardium in a Case of Enterovesical Fistula

The use of graft materials in bladder mucosa has been examined in animal models, but debate exists over which materials are effective. Intestine has been used as a substitute in augmentation cystoplasty for patients with neuropathic bladder, but serious adverse effects of the operation have occurred in some instances. We report a case of a successful repair of an enterovesical fistula by use of bovine pericardium. The patient has remained well for 2.5 years. We suggest that bovine pericardium may be a suitable option as a bladder substitute

Circulating Mesenchymal Stem Cells Microparticles in Patients with Cerebrovascular Disease

Preclinical and clinical studies have shown that the application of CD105+ mesenchymal stem cells (MSCs) is feasible and may lead to recovery after stroke. In addition, circulating microparticles are reportedly functional in various disease conditions. We tested the levels of circulating CD105+ microparticles in patients with acute ischemic stroke. The expression of CD105 (a surface marker of MSCs) and CXCR4 (a CXC chemokine receptor for MSC homing) on circulating microparticles was evaluated by flow cytometry of samples from 111 patients and 50 healthy subjects. The percentage of apoptotic CD105 microparticles was determined based on annexin V (AV) expression. The relationship between serum levels of CD105+/AV− microparticles, stromal cells derived factor-1α (SDF-1α), and the extensiveness of cerebral infarcts was also evaluated. CD105+/AV− microparticles were higher in stroke patients than control subjects. Correlation analysis showed that the levels of CD105+/AV− microparticles increased as the baseline stroke severity increased. Multivariate testing showed that the initial severity of stroke was independently associated with circulating CD105+/AV− microparticles (OR, 1.103 for 1 point increase in the NIHSS score on admission; 95% CI, 1.032–1.178) after adjusting for other variables. The levels of CD105+/CXCR4+/AV− microparticles were also increased in patients with severe disability (r = 0.192, p = 0.046 for NIHSS score on admission), but were decreased with time after stroke onset (r = −0.204, p = 0.036). Risk factor profiles were not associated with the levels of circulating microparticles or SDF-1α. In conclusion, our data showed that stroke triggers the mobilization of MSC-derived microparticles, especially in patients with extensive ischemic stroke

Incremental information content of cash flow variables: A spanning approach

This study investigates whether alternative cash flow measures have an incremental information content over accounting measure. This study employes the arbitrage argument to establish an economic model which makes it possible to incorporate raw accounting variables into a return generating process. Based on the economic model, a new methodology, the spanning portfolio approach is used to extract the information contained in the accounting measures of cash flow. This issue is first examined by testing for an association between actual security returns and spanning returns of alternative cash flow measures. Secondly, the issue is analyzed in the context of explaining market risk. The results indicate that both cash flow and accrual accounting earnings have incremental information content relative to each other in explaining the actual security returns. Also, the results reveal that, in explaining market risk, only cash flow has information consistent with that contained in market risk measure (market beta) and provides significant incremental information over that provided by earnings. These findings imply that the accrual adjustment process in accounting may not be valuable at least for assessing the company's systematic risk.U of I OnlyETDs are only available to UIUC Users without author permissio

TMD-based structural control of high performance steel bridges

The purpose of this study is to investigate the effectiveness of structural control using tuned mass damper (TMD) for suppressing excessive traffic induced vibration of high performance steel bridge. The study considered 1-span steel plate girder bridge and bridge-vehicle interaction using HS-24 truck model. A numerical model of steel plate girder, traffic load, and TMD is constructed and time history analysis is performed using commercial structural analysis program ABAQUS 6.10. Results from analyses show that high performance steel bridge has dynamic serviceability problem, compared to relatively low performance steel bridge. Therefore, the structural control using TMD is implemented in order to alleviate dynamic serviceability problems. TMD is applied to the bridge with high performance steel and then vertical vibration due to dynamic behavior is assessed again. In consequent, by using TMD, it is confirmed that the residual amplitude is appreciably reduced by 85% in steady-state vibration. Moreover, vibration serviceability assessment using 'Reiher-Meister Curve' is also remarkably improved. As a result, this paper provides the guideline for economical design of I-girder using high performance steel and evaluates the effectiveness of structural control using TMD, simultaneously

Finite Element Investigation of Load Acting on the Hotspot Detector Located inside the Silo Caused by Material Discharge

Spontaneous ignition caused by material discharge inside a silo causes considerable economic damage. To prevent this, we developed a silo hotspot detector that can be installed inside the silo to monitor the temperature according to the depth of the silo. However, if the silo hotspot detector located inside the silo is destroyed because of the pressure and load generated during material discharge, it could lead to a larger accident. Therefore, the structural safety of the silo hotspot detector should be evaluated based on material discharge; currently, there is no particular method to achieve this. Therefore, in this study, the theoretical formula is obtained through Eurocode, and the pressure and tensile force acting on the silo hotspot detector are predicted through the finite element method (FEM) using the Coupled Eulerian–Lagrangian(CEL) method. These result were verified by comparing the load measurement data acting on the silo hotspot detector when the silo material was discharged. It was confirmed that simulation using the CEL method can sufficiently simulate the behavior of the silo according to material discharge. Additionally, we confirmed that the structural safety of the silo hotspot detector inside the silo can be evaluated through FEM

Optimization of Position and Number of Hotspot Detectors Using Artificial Neural Network and Genetic Algorithm to Estimate Material Levels Inside a Silo

To realize efficient operation of a silo, level management of internal storage is crucial. In this study, to address the existing measurement limitations, a silo hotspot detector, which is typically utilized for internal silo temperature monitoring, was employed. The internal temperature data measured using the hotspot detectors were used to train an artificial neural network (ANN) algorithm to predict the level of the internal storage of the silo. The prediction accuracy was evaluated by comparing the predicted data with ground truth data. We combined the ANN model with the genetic algorithm (GA) to improve the prediction accuracy and establish efficient sensor installation positions and number to proceed with optimization. Simulation results demonstrated that the best predictive performance (up to 97% accuracy) was achieved when the ANN structure was 9-19-19-1. Furthermore, the numbers of efficient sensors and sensors positions determined using the proposed ANN-GA technique were reduced from seven to five or four, thereby ensuring economic feasibility

Local deformed diameter analysis of a pipe in rigid encasement for water-crossings application

This article presents a new type of stress assessment method for double-layered pressure vessel. Due to its robust strength, a steel-concrete composite pipe is generally installed in poor burial conditions. However, it is difficult to directly define the stress state on pipe sections. For the convenient stress estimation of pipes encased in non-circular concrete, this article suggests a Stress Index (SI), a function of the interface pressure and changed diameter, based on the interface pressure. The ovalization characteristics of plain pipes and of pipes encased by circular and rectangular concrete are examined. The resultant stresses are replaced by the non-dimensional ratio of diameter change; thus, the stress index has the advantage of application for stress assessment irrespective of pipe characteristics. ?? 2013 Springer Science+Business Media