Structural Control of Piezoelectric Laminated Beams under Thermal Load

The dynamic analysis and the active vibration control of piezoelectric laminated beams under thermal load are presented. The beam is modeled using two noded finite elements with four mechanical and a variable number of electric potential degrees of freedom at each node. In the thickness direction, the thermal and the electric fields are approximated as piecewise linear across an arbitrary number of sublayers in a layer. Cubic Hermite interpolation is used for the deflection and electric potentials at the sublayers and linear interpolation is used for the axial displacement and the shear rotation. The thermal field is computed using a consistent six-noded thermal finite element with a quadratic interpolation along longitudinal direction and a linear interpolation along thickness direction. The temperature distribution and undamped natural frequencies are obtained for composite and sandwich beam under cantilever and clamped-clamped boundary conditions and compared with 2D-FE Abaqus results. The finite element equations derived are converted into modal model to represent them in the state space form. This model is then reduced using Hankel norm for designing the LQG controller. Optimal control technique is used to control the vibration of the beam. The designed LQG controller controls the tip deflection of composite and sandwich cantilever beams and midpoint deflection of clamped-clamped beams.     

Effects of macro-parameters on vibration and radiation noise for high speed wheel gear transmission in electric vehicles

Considering flexible shafts, a coupled dynamic model for the gear transmission system of wheel reducer used in electric vehicle was developed. By combining the acoustics finite element modal for housing in Virtual Lab and the coupled dynamic model for gear transmission system, a simulation method was proposed for the prediction of the radiation noise for the wheel reducer. Then, the effects of different macro geometry gear parameters including pressure angle and helical angle on the dynamic response and radiation noise were investigated under the rated working condition. Results show that the peak-peak value of the transmission error dramatically falls in the starting zone, followed by an upward trend with the increase of the pressure angle for the low speed stage gear pair. The minimum transmission error and vibration acceleration occur when the pressure angle is 17°. The increase of the pressure angle does not affect the sound pressure level at the field point obviously. The design case with 17° pressure angle shows the optimum radiation noise level, which is 4.41dB less than the original model. Compared to the pressure angle, the helix angle has a major influence on the transmission error, vibration acceleration and acoustic radiation noise. With the increase of the helix angle, the time-varying transmission error curve becomes more smooth with a lower peak-peak value. Besides, the increase of helix angle results in lowering the varying and fluctuating trend of both vibration acceleration and acoustic radiation noise. The design case with 24° helix angle shows the prime radiation noise level, which is 7 dB less than the original scheme.     

Biohydrogen production from agroindustrial wastes via Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564)

The anaerobic production of biohydrogen from different pretreated agroindustrial wastes, including rice bran (RB), de-oiled RB (DRB), sago starch (SS), and palm oil mill effluent (POME) via Clostridium saccharoperbutylacetonicum N1-4 was investigated in a batch culture system at 30 °C and a pH of 6.2. A yield of 7627, 6995, and 6,363 mL H₂/L was obtained from H₂SO₄ (1 %)-treated DRB (10 %), enzymatically hydrolyzed DRB (10 %) and HCl (1 %)-treated DRB (10 %), respectively; however, untreated DRB (10 %) was able to produce only 3,286 mL H₂/L. A strategic treatment of RB (10 %) with HCl (1 %) followed by enzymatic hydrolysis could produce 3,172 mL H₂/L. An enzymatically hydrolyzed mixture of each POME and SS (5 %) produced 3,474 mL H₂/L, and a remarkable enhancement of H₂ production (7,020 mL H₂/L) was achieved when the same mixture was subjected to XAD-4 resin treatment. In contrast, the enzymatically hydrolyzed SS (5 %) could produce only 4,628 mL H₂/L. Conclusively, it can be stated that agricultural wastes have a potential as substrates for biohydrogen production and that pretreatment with C. saccharoperbutylacetonicum N1-4 can contribute positively to enhancing the production.     

Association of Methylentetraydrofolate Reductase (MTHFR) 677 C > T gene polymorphism and homocysteine levels in psoriasis vulgaris patients from Malaysia: a case-control study

Background  

The methylenetetrahydrofolate reductase (MTHFR) enzyme catalyzes the reduction of 5, 10-methylenetetrahydrofolate to 5-methyltetrahydrofolate and methyl donors. The methyl donors are required for the conversion of homocysteine to methionine. Mutation of MTHFR 677 C > T disrupts its thermostability therefore leads to defective enzyme activities and dysregulation of homocysteine levels.     

Synthesis and characterization of PHV-block-mPEG diblock copolymer and its formation of amphiphilic nanoparticles for drug delivery

Despite the recent research interest in the field of nanoparticles delivery system, their structure modification and transport behavior of various hydrophobic drugs is poorly developed. In this article the synthesis of novel amphiphilic diblock copolymer poly([R]-3-hydroxyvalerate)-block-monomethoxy poly(ethylene glycol) (PHV-block-mPEG) was undertaken by modifying the structure of biodegradable and hydrophobic poly([R]-3-hydroxyvalerate) (PHV) with hydrophilic monomethoxy poly(ethylene glycol) (mPEG). The chemical combination of the two blocks was carried out in the melt using bis(2-ethylhexanoate) tin as transesterification catalyst. The synthesized product was characterized by gel permeation chromatography (GPC), 1H nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC) analysis. The block copolymer self-assembled into amphiphilic nanoparticles with a core of hydrophobic PHV and a shell of hydrophilic mPEG in aqueous solution. Characterization of the nanoparticles showed the formation of discrete, spherically shaped nanoparticles with mean particle size of 200 +/- 1 nm and zeta potential of -14 +/- 1 mV. A hydrophobic drug thymoquinone was efficiently incorporated into the core hydrophobic domain of the nanoparticles and its release kinetics was studied in vitro. The amphiphilic PEGylated nanoparticles showed biocompatibility when checked in neuronal hippocampal cells of prenatal rat. Our results suggest that the amphiphilic nanoparticles with core-shell structures are potentially useful to develop novel drug carriers.     

A review of retinal blood vessels extraction techniques: challenges,taxonomy, and future trends

Pattern Analysis and Applications - The visual exploration of retinal blood vessels assists ophthalmologists in the diagnoses of different abnormalities of the eyes such as diabetic retinopathy,...     

Intelligent computing approach to analyze the dynamics of wire coating with Oldroyd 8-constant fluid

Neural Computing and Applications - In the study, intelligent computing technique is developed for solving the nonlinear system for wire coating analysis with the bath of Oldroyd 8-constant fluid...     

Hydrogen production using Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564)

Fermentative hydrogen production was carried out using Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564). This work investigates the effects of initial substrate concentration, initial medium pH, and temperature. The hydrogen yield was about 3.1 mol (mol glucose)⁻¹ when starting with an initial glucose concentration of 10 gl⁻¹ and initial a pH of 6.0 ± 0.2 at a temperature of 37 °C. The volume of hydrogen produced decreased when higher initial glucose concentrations were applied. The most suitable conditions for hydrogen production in a batch reactor were observed at initial pH 6.0 ± 0.2 and 37 °C.     

Combined Blockiness,Blurriness and White Noise Distortion Meter

Due to discrete cosine transform (DCT) based compression, the loss appears in the form of blocky and blurry distortions in coded pictures. One of the degradation is white noise which corrupts nearly all pixels in the picture. In image transmission system, to assess the image quality at receiver end, lesser image features are sent, instead of the whole reference original picture to accommodate the available bandwidth. The purpose of this research is to propose a procedure which quantifies or estimates the objective picture quality automatically. The presented combined white noise image quality assessment meter (CWNIQAM) functions in the frequency domain for computation of three artefacts blockiness, blurriness and white noise in the corrupted coded images. The designed quality meter at first converts RGB pictures into YC_bC_r, gray scaled pictures and then edge detection method is applied. Afterward the picture is divided into blocks of 32 × 32 pixels to get local level blockiness, blurriness and white noise value. Next the picture is transformed from spatial to frequency domain and different features called reduced reference parameters are estimated. The composite magnitudes strength through horizontal and vertical harmonics is obtained for estimation of blocky and blurry artefacts in the coded images, while the strength of all ac coefficients and dc component is obtained for computation of white noise. The reduced reference features are computed and compared for reference and coded picture for estimating the particular type of distortion. The uniqueness of the proposed CWNIQAM meter is that, it can estimate the quality of corrupted images by estimating the combination of blockiness, blurriness and white noise through this single meter. The LIVE database2 having 174 different white noise (wn) corrupted images are used for measuring combined objective value of the three artefacts using the designed reduced reference image quality assessment meter algorithm. The objective results are correlated with subjective wn, DMOS LIVE scores. The correlation of about 98% is attained which indicate that much better picture quality index is achieved by the offered reduced reference combined white noise image quality evaluation meter in the frequency domain.