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Analytical and finite-element study of optimal strain distribution in various beam shapes for energy harvesting applications

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Acta Mechanica Sinica 2016年第4期32卷 670-683页

作者： B.L.Ooi j.M.Gilbert A.Rashid A.aziz Faculty of Integrative Sciences and Technology Quest International University Perak (QIUP) Faculty of Science and Engineering School of EngineeringUniversity of Hull Center for Automotive Research and Electric Mobility(CAREM) Universiti Teknologi PETRONAS (UTP)

Owing to the increasing demand for harvesting energy from environmental vibration for use in self-powered electronic applications, cantilever-based vibration energy harvesting has attracted considerable interest from various parties and has become one of the most common approaches to converting redundant mechanical energy into electrical energy. As the output voltage produced from a piezoelectric material depends largely on the geometric shape and the size of the beam, there is a need to model and compare the performance of cantilever beams of differing *** paper presents the study of strain distribution in various shapes of cantilever beams, including a convex and concave edge profile elliptical beam that have not yet been discussed in any prior literature. Both analytical and finite-element models are derived and the resultant strain distributions in the beam are computed based on a MATLAB solver and ANSYS finite-element analysis tools. An optimum geometry for a vibration-based energy harvesting system is ***, experimental results comparing the power density for triangular and rectangular piezoelectric beams are also presented to validate the findings of the study, and the claim, as suggested in the literature, is verified.

关键词： harvesting triangular elliptical verified normalized piezoelectric cantilever redundant validate rectangular

Fabrication of novel ZnO/MnWO_4 nanocomposites with p-n heterojunction: Visible-light-induced photocatalysts with substantially improved activity and durability

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journal of Materials Science & Technology 2018年第10期34卷 1891-1901页

作者： Mahsa Pirhashemi aziz Habibi-Yangjeh Department of Chemistry Faculty of Science University of Mohaghegh Ardabili P.O. Box 179 Ardabil Iran

We report, for the first time, binary ZnO/MnW04 nanocomposites with p-n heterojunction fabricated by a simple ultrasonic-calcination route. The phase structure, morphology, and optical along with tex- tural properties were comprehensively characterized. The photocatalytic performance was studied via degradations of rhodamine B, methyl blue and methyl orange （RhB, MB, MO）, and fuchsine pollutants under visible-light illumination. The ZnO/MnW04 nanocomposites exhibited better photocatalytic per-formance than their single components and the nanocomposite with 30 wt% MnW04 showed the highest activity. Photocatalytic performance of this nanocomposite is 22.5, 17.7, 26.8, and 23.9 times higher than that of the ZnO sample in degradations of RhB, MB, MO, and fuchsine dyes, respectively. The improved photocatalytic performance was ascribed to the formation ofp-n heterojunction between ZnO and MnW04 with high charge separation efficiency as well as strong visible-light absorption ability. The possible mechanism for the improved photocatalytic performance was proposed. This study revealed that the novel ZnO/MnW04 p-n heterojunction can act as a promising visible-light-active photocatalyst for environmental applications.

关键词： ZnO/MnW04 p-n heterojunction Visible-light-active Photocatalyst

Erosion and runoff reduction potential of vetiver grass for hill slopes:A physical model study

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International journal of Sediment Research 2023年第1期38卷 49-65页

作者： Shamontee aziz Mohammad Shariful Islam BUET-japan Institute of Disaster Prevention and Urban Safety (BUET-jIDPUS) Bangladesh University of Engineering and Technology (BUET) Department of Civil Engineering Bangladesh University of Engineering and Technology (BUET)

Severe erosion is caused by intense rainfall in tropical regions. The erodible soil of steep hill slopes,accompanied by destruction of vegetation due to human interventions results in accelerated erosion. A sustainable and cost-effective solution such as vetiver grass(Chrysopogon zizanioides) is, thus, required to control the erosion process. In the current study, 6 small-scale glass models: 1 bare and 5 with vetiver grass, having a slope angle of 37°have been constructed. One year after planting, artificial rainfall of extremely high intensity was applied to all 6 small models and the role of vetiver canopy and roots in erosion and runoff control was observed. To see the effect of soil texture, one among these 5 models was made with silty sand and others contained sandy silt. The results demonstrated that, for sandy silt, the inclusion of vetiver reduced the soil loss by 94%-97%, and soil detachment rates were lowered by 95%.The average runoff also was reduced by 21%. The canopy cover showed a positive impact on reducing both quantities. An increase in average root diameter from 1.6 to 2.5 mm increases the soil loss due to its negative impact on added cohesion. The added cohesion showed a linearly negative correlation with soil loss. A composite system of vetiver and jute geotextile was most effective in erosion reduction among 4vegetated models with sandy silt. Under same vetiver planting layout, the grass covered model of silty sand yielded 84% lower erosion and 62.5% lower runoff than the grass covered one with sandy silt. Thus,vetiver was more effective in erosion and runoff reduction for soil with a greater percentage of sand, and soil type dominated the erosion process.

关键词： Erosion Small-scale model experiments Surface runoff Artificial rainfall Vetiver

Efficacy of Cordyceps sinensis as an adjunctive treatment in hemodialysis patients: a systematic review and Meta-analysis

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journal of Traditional Chinese Medicine 2019年第1期39卷 1-14页

作者： Bee Yean Ong Zoriah aziz Department of Pharmacy Faculty of MedicineUniversity of MalayaKuala Lumpur 50603Malaysia

OBjECTIVE: To evaluate current evidence on the efficacy and safety of Cordyceps sinensis(cordyceps)or its fermented products used as an adjunctive treatment in patients undergoing maintenance ***: The Cochrane Central Register of Controlled Trials(CENTRAL), EMBASE, MEDLINE, China National Knowledge Infrastructure(CNKI) and Wanfang Database were searched for relevant randomized controlled trials up to March 2016. Two review authors independently selected trials for inclusion,extracted data, assessed the methodological quality and rated the quality of evidence with the Grading of Recommendations, Assessment, Development and Evaluation ***: Twelve studies involving 655 participants were included. Evidence of low to moderate-quality showed that cordyceps plus conventional treatment compared to conventional treatment alone significantly improved C-reactive protein [standardized mean difference(SMD)-0.61; 95% confi-dence intervals(CI)-1.00 to-0.22], high-sensitivity C-reactive protein [weighted mean difference(WMD)-3.44 mg/L; 95% CI-3.89 to-2.99], serum albumin(WMD 3.07 g/L; 95% CI 1.59 to 4.55),malondialdehyde(WMD-1.95 nmol/L; 95% CI-2.24 to-1.66), and hemoglobin(WMD 9.56 g/L;95% CI 3.65 to 15.47) levels. However, there was no significant improvement for serum creatinine and low-density lipoprotein cholesterol. Overall, most trials either did not monitor adverse events or poorly documented ***: Given the small number of trials included, the unclear methodological quality of the included trials, and the high heterogeneity in pooled analyses, the evidence obtained in this review is insufficient to recommend the use of cordyceps as adjunctive treatment in hemodialysis patients.

关键词： Cordyceps sinensis Renal dialysis C-reactive protein Albumin Adjunctive treatment Meta-analysis

A toughness based deformation limit for X- and K-joints under brace axial tension

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Frontiers of Structural and Civil Engineering 2016年第3期10卷 345-362页

作者： Bo GU Xudong QIAN aziz AHMED Department of Civil and Environmental Engineering National University of Singapore 1 Engineering Drive 2 Singapore 117576 Singapore

This study reports a deformation limit for the initiation of ductile fracture failure in fatigue-cracked circular hollow section （CHS） X- and K-joints subjected to brace axial tension. The proposed approach sets the deformation limit as the numerically computed crack driving force in a fatigue crack at the hot-spot location in the tubular joint reaches the material fracture toughness measured from standard fracture specimens. The calibration of the numerical procedure predicates on reported numerical computations on the crack driving force and previously published verification study against large-scale CHS X-joints with fatigue generated surface cracks. The development of the deformation limit includes a normalization procedure, which covers a wide range of the geometric parameters and material toughness levels. The lower-bound deformation limits thus developed follow a linear relationship with respect to the crack-depth ratio for both X- and K-joints. Comparison of the predicated deformation limit against experimental on cracked tubular X- and K- joints demonstrates the conservative nature of the proposed deformation limit. The proposed deformation limit, when extrapolated to a zero crack depth, provides an estimate on the deformation limits for intact X- and K-joints under brace axial loads.

关键词： circular hollow section (CHS) tubular joint fracture failure deformation limit j-integral

Numerical modelling of the stress in the Pamir-Hindu Kush region

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Geodesy and Geodynamics 2022年第1期13卷 83-91页

作者： Ikram Atabekov Mirzoid Muminov aziz Atabekov Institute of Seismology Tashkent100128Uzbekistan National University of Uzbekistan Tashkent100174Uzbekistan

The current stress state of the Earth's crust in Central Asia depends entirely on the interaction of the Eurasian plate with the Indian and Arabian ***,an essential role in this action is played by the subduction process in the Pamir-Hind Kush *** this region,deep earthquakes and anomalies in seismic velocities indicate subduction of the Indian *** determine the effect of earthquakes on the stress state of the Earth's crust in Central Asia,we analyzed the hypocenters according to the available data over a hundred *** the envelope of the hypocenters as the surface of the subducted indenter,we analyzed its penetration into the *** of the pushing force of the indenter,the velocity of the Indian plate is taken into consideration.A model of the stresses is constructed on the equations of creeping motion of a viscous incompressible *** stress variation in the Earth's crust and mantle was calculated as the stress difference before and after the *** mechanism of earthquakes is modelled by an introduction of equivalent volume forces in the equilibrium equations corresponding to a couple dipoles without a *** equations of creeping motion are numerically solved using boundary element *** experiments with different physical model pa-rameters for the Earth's crust and mantle were *** introduce the negative buoyancy of the subducting plate,partial eclogitization of the rocks in the collision zone was *** a result,a certain combination of stiffness and density was determined for the lithosphere and mantle,which explained the peculiarities of this *** influence of crustal and mantle earthquakes in the Pamir-Hindu Kush region on the change in background stresses in Central Asia was analyzed which are not higher than 2-3%.

关键词： Pamir-hindu kush Stress state Mantle earthquakes Boundary element method

Novel ternary g-C_3N_4/Fe_3O_4/MnWO_4 nanocomposites: Synthesis,characterization, and visible-light photocatalytic performance for environmental purposes

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journal of Materials Science & Technology 2018年第9期34卷 1638-1651页

作者： Mitra Mousavi aziz Habibi-Yangjeh Davod Seifzadeh Department of Chemistry Faculty of Science University of Mohaghegh Ardabili

The g-C3 N4/Fe3 O4/MnWO4 nanocomposites were prepared by a refluxing-calcination procedure. Visiblelight-induced photocatalytic experiments showed that the g-C3 N4/Fe3 O4/MnWO4（10%） nanocomposite has excellent ability to degrade a range of contaminants including rhodamine B, methylene blue, methyl orange, and fuchsine, which is about 7, 10, 25, and 31 times of the g-C3 N4 photocatalyst, *** species trapping experiments revealed that superoxide anion radicals play major role in the photodegradation reaction of rhodamine B（RhB）. After the treatment process, the utilized photocatalyst was magnetically recovered and reused with negligible loss in the photocatalytic activity, which is vital in the photocatalytic processes. Finally, a mechanism was proposed for the enhanced interfacial carrier separation and transfer and the improved photocatalytic performance.

关键词： g-C3N4/Fe3O4/MnWO4 Magnetically recoverable photocatalyst Visible-light photocatalyst Wastewater

Mathematical modeling of contact tracing and stability analysis to inform its impact on disease outbreaks;an application to COVID-19

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Infectious Disease Modelling 2024年第2期9卷 329-353页

作者： Mohamed Ladib aziz Ouhinou Abdul-aziz Yakubu University of Sultan Moulay Slimane Faculty of Sciences and TechniquesTeam of Mathematics and InteractionsBéni-MellalMorocco Howard University Dept MathWashingtonDC20059USA

We develop a mathematical model to investigate the effect of contact tracing on containing epidemic outbreaks and slowing down the spread of transmissible *** propose a discrete-time epidemic model structured by disease-age which includes general features of contact *** model is fitted to data reported for the early spread of COVID-19 in South Korea,Brazil,and *** calibrated values for the contact tracing parameters reflect the order pattern observed in its performance intensity within the three *** the fitted values,we estimate the effective reproduction number R_(e)and investigate its responses to varied control scenarios of contact *** the positivity of solutions,and a stability analysis of the disease-free equilibrium are provided.

关键词： Mathematical modeling Infectious diseases Discrete systems Disease-age structured populations Contact tracing Effective reproduction number COVID-19

Synthesis of magnetically recoverable visible-light-induced photocatalysts by combination of Fe3O4/ZnO with BiOI and polyaniline

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Progress in Natural Science:Materials International 2019年第2期29卷 145-155页

作者： aziz Habibi-Yangjeh Maryam Shekofteh-Gohari Department of Chemistry Faculty of Science University of Mohaghegh Ardabili

Magnetically recyclable photocatalysts with efficient performances under visible light were synthesized by combining Fe3O4/ZnO with BiOI and polyaniline（PANI）. The FT-IR, XRD, HRTEM, SEM, EDX, XPS, UV–vis DRS,VSM, BET, and PL instruments were utilized for characterization of the as-prepared products. The activity tests exhibited that the superior rate constant in photocatalytic performance was achieved over the Fe3O4/ZnO/BiOI/PANI（20%） nanocomposite, which enhanced for more than 59.9, 10.0, and 6.57 times, as compared to those of the Fe3O4/ZnO, Fe3O4/ZnO/PANI, and Fe3O4/ZnO/BiOI photocatalysts in degradation of RhB, *** photocatalytic degradations of MO/MB and photo reduction of Cr（VI） were also investigated to confirm the potential application of the photocatalyst in removal of various pollutants. The considerably enhanced activity pointed to a promoting effect of p-n-p heterojunctions formed between PANI, ZnO, and BiOI, and improved textural characteristics, which are benefit for improvement of the photocatalytic performances.

关键词： Fe3O4/ZnO/BiOI/PANI Heterojunction Magnetically recoverable photocatalyst Visible-light-driven photocatalyst