Performance of an earth wall stabilized with bearing reinforcements

This article presents the performance of a fully instrumented test wall reinforced with bearing reinforcement. Bearing reinforcement is an inextensible earth reinforcement. It is composed of a longitudinal member and transverse members. The longitudinal member is a deformed steel bar and the transverse members are a set of equal steel angles. The test wall was 6 m high, 9 m long at the top, 6 m wide at the top, and 12 m long, 21 m wide at the base and was constructed on a hard stratum. The facing panels were made of segmental concrete block which measured 1.50 × 1.50 × 0.14 m in dimension. From the full-scale test results, the bearing stress distribution is a trapezoid shape as generally assumed for the examination of the external stability of MSE walls. The tilt of the bearing reinforcement earth (BRE) wall indicates that the BRE wall behaves as a rigid body. The coefficients of earth pressure decrease with depth and approach the active state at deeper reinforcement level. From the variation in the stiffness factor as a function of depth and lateral earth pressure, the bearing reinforcement has a stiffness factor of K/K_a = 1.7, which is much lower than that of steel grids and metal strips. The lower tension (coefficient of lateral earth pressure) reduces the cross-sectional area of the longitudinal members and hence cost effectiveness. The maximum tension line (possible failure plane) of the BRE wall is bilinear, similarly to the coherent gravity structure hypothesis, which is commonly used for the analysis of inextensible reinforcements. Finally, the suggested method of designing the BRE wall is presented. It has been successfully used to design several BRE walls founded on the hard stratum in different areas in Thailand.     

A novel discrete wavelet transform based on traveling wave technique for identifying the fault location for transmission network systems

This paper proposes a technique to identify fault location on transmission systems using discrete wavelet transforms (DWTs). Fault conditions are simulated using alternative transients program/electromagnetic transients program (ATP/EMTP) in order to obtain the current signals. Various cases based on Thailand electricity transmission systems are studied to verify the validity of the proposed technique. The comparisons among the maximum coefficients in first scale of all buses that can detect fault are performed to detect the faulty bus. The first peak time of positive sequence current obtained from the faulty bus is used as input data for the traveling wave equation. It is shown that the proposed technique gives satisfactory accuracy and is suitable for all types of fault occurring in different sections of transmission lines. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

An accurate forearm EMG signal classification method using two‐channel electrode

An accurate electromyography (EMG) classification algorithm to control a virtual hand prosthesis with 12 degrees of freedom using two surface EMG electrodes is presented in this paper. We propose the application of independent component analysis (ICA) for blind‐source separation of the EMG signals obtained from two electrodes. One of the problems affecting the EMG classification accuracy is the location dependence of the EMG signal due to the superposition of signals from multiple sources. ICA is used to separate the two signals obtained from two surface electrodes into two independent EMG signals prior to the feature extraction and classification processes. We demonstrate that the EMG classification accuracy can be improved using the ICA algorithm. We also propose a novel eigen‐based feature that is extracted from the short‐time Fourier transform (STFT) magnitude spectrum. Our new feature not only decreases feature dimensions but also performs better than other well‐known features. We also implement the EMG classification scheme on the virtual robot arm. The performance shows promising result as indicated by a decrease in the Davies–Bolden (DB) index after applying the ICA © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Distributed Denial of Service (DDoS) detection by traffic pattern analysis

In this paper, we propose a behavior-based detection that can discriminate Distributed Denial of Service (DDoS) attack traffic from legitimated traffic regardless to various types of the attack packets and methods. Current DDoS attacks are carried out by attack tools, worms and botnets using different packet-transmission rates and packet forms to beat defense systems. These various attack strategies lead to defense systems requiring various detection methods in order to identify the attacks. Moreover, DDoS attacks can craft the traffics like flash crowd events and fly under the radar through the victim. We notice that DDoS attacks have features of repeatable patterns which are different from legitimate flash crowd traffics. In this paper, we propose a comparable detection methods based on the Pearson’s correlation coefficient. Our methods can extract the repeatable features from the packet arrivals in the DDoS traffics but not in flash crowd traffics. The extensive simulations were tested for the optimization of the detection methods. We then performed experiments with several datasets and our results affirm that the proposed methods can differentiate DDoS attacks from legitimate traffics.     

Thermally crosslinkable poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA)/polyvinyl alcohol (PVA) ion-exchange fibers

The aim of this study was to prepare poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA)/polyvinyl alcohol (PVA) ion-exchange fibers using the electrospinning technique and a post-thermal treatment. First, intermediate PSSA-MA/PVA fibers were prepared from solutions of PSSA-MA/PVA combined at ratios of 0.2/1 to 1/1; the fibers were subsequently crosslinked at 80–150 °C for 0.25–7 h. The effect of the crosslinking time, the temperature and the PSSA-MA/PVA ratio on various properties of the obtained ion-exchange fibers was investigated. When the PSSA-MA/PVA ratios were greater than 0.4/1, bead formation was observed. Thus, only smooth fibers without beads prepared from PSSA-MA/PVA mixed in ratios up to 0.4/1 were subjected to the thermal crosslinking treatment. When the crosslinking time and temperature were increased, the degree of crosslinking increased, which caused a decrease in the water solubilization and water uptake and an increase in the Young’s modulus. These parameters also appeared to significantly affect the ion-exchange capacity value. The temperature and time for successful crosslinking were 120–140 °C and 1–7 h, respectively.     

Effects of processing parameters on morphology of electrospun polystyrene nanofibers

This study focused on the preparation of electrospun polystyrene (PS) nanofibers. PS solutions were prepared in single (dimethylformamide; DMF, dimethylacetamide; DMAc or tetrahydrofuran; THF) and mixed solvent (DMF/THF and DMAc/THF) systems with and without tetrabutylammonium bromide (TBAB) salt. The effects of PS concentration, solvent system, the addition of salt, appearance and diameter of PS fibers were examined. The average diameter of the as-spun fibers increased upon increasing PS concentration. The morphology of the fibers significantly depended on the properties of the solvents. The obtained fibers were smooth without any beads and their diameters were affected by the amount of THF in the solvent and PS concentration. The beads in the fibers disappeared and the fiber diameter significantly decreased after the addition of TBAB. The smallest diameter and the narrowest diameter distribution of PS nanofibers (376±36 nm) were obtained from 15% PS solution in DMAc with 0.025% w/v TBAB.     

Formulation and evaluation of meloxicam oral disintegrating tablet with dissolution enhanced by combination of cyclodextrin and ion exchange resins

Context: The bitter taste of drug is masked by the exchange of ionized drugs with counter ions of ion exchange resin, forming “resinate”. Cyclodextrin reduces the unpleasant taste and enhances the drug solubility by encapsulating drug molecules into its central cavity.

Objective: Oral disintegrating tablets (ODTs) using the combination of ion exchange resin and cyclodextrin was developed, to mask the bitter taste and enhance drug dissolution.

Methods: Meloxicam (MX) was selected as a model drug. Formulations containing various forms of MX (free drug, MX-loaded resin or resinate, complexes of MX and 2-hydroxypropyl-β-cyclodextrin (HPβCD) or MX/HPβCD complexes, and a mixture of resinate and MX/HPβCD complexes) were made by direct compression. The ODTs were evaluated for weight variation, thickness, diameter, hardness, friability, disintegration time, wetting time, MX content, MX release, degree of bitter taste and stability.

Results and discussion: The tablet hardness was ～3?kg/in², and the friability was <1%. Tablets formulated with resinate and the mixture of resinate and MX/HPβCD complexes disintegrated rapidly within 60?s, which is the acceptable limit for ODTs. These results were corresponded to the in vivo disintegration and wetting times. However, only tablets containing the mixture of resinate and MX/HPβCD complexes provided complete MX dissolution and successfully masked the bitter taste. In addition, this tablet was stable at least 6 months.

Conclusions: The combination of ion exchange resin and cyclodextrin could be used in ODTs to mask the bitter taste and enhance the dissolution of drugs that are weakly soluble in water.     

Evaluation of new parboiled rice process using humidified hot air fluidized bed drying

This study aims to experimentally investigate the drying characteristics and quality of a paddy dried by hot air (HA) and humidified hot air (HHA) fluidization technique. Qualities such as head rice yield (HRY), white belly, degree of gelatinization (DSG), and color of dried paddy were evaluated. A paddy with an initial moisture content of 14% d.b. was soaked in hot water at a temperature of 70?°C for 5?h then dried at a temperature of 130,150, and 170?°C, relative humidity in the range of 0.3–12%, an air velocity of 3.9 m/s, and a bed height of 10?cm. The results showed that the drying time of the paddy in the HHA condition took longer than the HA drying condition. Because HHA provided a higher grain temperature and a slow rate of drying, the degree of starch gelatinization was significantly higher when compared to HA. The subsequent HRY was relatively higher than using HA drying. However, the color of the sample obtained from the HHA condition was relatively browner, but the parboiled rice product still had a light brown color for the drying temperature range used in this study. To produce parboiled rice, HHA could be operated up to the temperature of 170?°C, relative humidity of 6%, and DOM of 10%.