ORCID Profile
0000-0002-6679-657X
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Publisher: IOP Publishing
Date: 20-03-2018
Publisher: Elsevier BV
Date: 12-2006
Publisher: Elsevier BV
Date: 02-2018
Publisher: Springer Science and Business Media LLC
Date: 20-01-2015
DOI: 10.1007/S13246-015-0328-7
Abstract: A passive deep brain stimulation (DBS) device can be equipped with a rectenna, consisting of an antenna and a rectifier, to harvest energy from electromagnetic fields for its operation. This paper presents optimization of radio frequency rectifier circuits for wireless energy harvesting in a passive head-mountable DBS device. The aim is to achieve a compact size, high conversion efficiency, and high output voltage rectifier. Four different rectifiers based on the Delon doubler, Greinacher voltage tripler, Delon voltage quadrupler, and 2-stage charge pumped architectures are designed, simulated, fabricated, and evaluated. The design and simulation are conducted using Agilent Genesys at operating frequency of 915 MHz. A dielectric substrate of FR-4 with thickness of 1.6 mm, and surface mount devices (SMD) components are used to fabricate the designed rectifiers. The performance of the fabricated rectifiers is evaluated using a 915 MHz radio frequency (RF) energy source. The maximum measured conversion efficiency of the Delon doubler, Greinacher tripler, Delon quadrupler, and 2-stage charge pumped rectifiers are 78, 75, 73, and 76 % at -5 dBm input power and for load resistances of 5-15 kΩ. The conversion efficiency of the rectifiers decreases significantly with the increase in the input power level. The Delon doubler rectifier provides the highest efficiency at both -5 and 5 dBm input power levels, whereas the Delon quadrupler rectifier gives the lowest efficiency for the same inputs. By considering both efficiency and DC output voltage, the charge pump rectifier outperforms the other three rectifiers. Accordingly, the optimised 2-stage charge pumped rectifier is used together with an antenna to harvest energy in our DBS device.
Publisher: Elsevier BV
Date: 06-2008
Publisher: Emerald
Date: 27-02-2009
Publisher: Elsevier BV
Date: 1998
Publisher: Elsevier BV
Date: 07-2007
Publisher: Elsevier BV
Date: 10-2017
Publisher: Elsevier BV
Date: 11-2017
DOI: 10.1016/J.APPET.2017.08.013
Abstract: Eating alone is driven by social and cultural factors, not solely by in idual preferences. In academic research, eating alone is often simply treated as an alternative to social, commensal eating, and little is known about the practice of eating alone itself. This study employs a cross-cultural analysis to explore social and cultural associations of eating alone. The analysis is based on 1) cultural domain data, derived from principal component analysis of freelist responses, a set of words or phrases related to the topic of eating alone and 2) in-depth interviews with 72 young adults aged 20-40 in urban Australia and Japan. Many Australian and Japanese young adult participants associated eating alone with both pleasure and stress of being isolated from others. However, the comparison of principal components between Australian and Japanese groups and gender subgroups showed cross-cultural variations and complexity in the context of eating alone including: locations and timings of eating alone, and associations with healthy/unhealthy eating. Analyses of interviews are included to deepen understandings of cultural domains. These key associations are influenced by a range of social and cultural environments such as fast food cultures, work and life environments, and the scope of public health nutrition programs. The association between eating alone and healthy eating among young adults indicates that in idualistic understandings of food intake in current public health nutrition programs are more favorable to eating alone and foster a gap between ideas of healthy eating and commensal eating as a cultural ideal.
Publisher: Elsevier BV
Date: 07-2006
Publisher: Elsevier BV
Date: 2007
Publisher: Elsevier
Date: 2016
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2014
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2014
Publisher: Elsevier BV
Date: 04-2006
Publisher: Elsevier BV
Date: 2012
Publisher: IEEE
Date: 08-2012
Publisher: MDPI AG
Date: 22-07-2016
DOI: 10.3390/MA9070609
Publisher: Springer Science and Business Media LLC
Date: 31-10-2018
Publisher: Elsevier BV
Date: 2007
Publisher: Wiley
Date: 17-10-1994
Publisher: Elsevier BV
Date: 2007
Publisher: Wiley
Date: 06-02-2015
DOI: 10.1002/PAT.3465
Publisher: Springer Science and Business Media LLC
Date: 06-12-2013
Publisher: Elsevier BV
Date: 12-2007
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2014
Publisher: Wiley
Date: 2005
DOI: 10.1002/ADV.20040
Publisher: Elsevier BV
Date: 10-2016
Publisher: MDPI AG
Date: 26-04-2020
DOI: 10.3390/APP10093020
Abstract: Building on the recent progress of four-dimensional (4D) printing to produce dynamic structures, this study aimed to bring this technology to the next level by introducing control-based 4D printing to develop adaptive 4D-printed systems with highly versatile multi-disciplinary applications, including medicine, in the form of assisted soft robots, smart textiles as wearable electronics and other industries such as agriculture and microfluidics. This study introduced and analysed adaptive 4D-printed systems with an advanced manufacturing approach for developing stimuli-responsive constructs that organically adapted to environmental dynamic situations and uncertainties as nature does. The adaptive 4D-printed systems incorporated synergic integration of three-dimensional (3D)-printed sensors into 4D-printing and control units, which could be assembled and programmed to transform their shapes based on the assigned tasks and environmental stimuli. This paper demonstrates the adaptivity of these systems via a combination of proprioceptive sensory feedback, modeling and controllers, as well as the challenges and future opportunities they present.
Publisher: MDPI AG
Date: 13-08-2013
DOI: 10.3390/MA6083482
Publisher: Elsevier BV
Date: 07-1996
Publisher: SAGE Publications
Date: 07-1992
DOI: 10.1177/1045389X9200300301
Abstract: Before conducting polymers can be employed in many applications, some of the intrinsic properties of these materials need to be better understood. An overview of the research and development of conducting polymers being undertaken at UTS is presented. Because conducting polymers are difficult to process once fabricated, an understanding of synthesis parameters and the use of synthesis techniques to pro duce conducting polymer films with desired properties is of the upmost importance. Descriptions of the galvanostatic and potentiostatic techniques employed to produce polyheterocyclics are presented. Thermal properties such as thermal diffusivity, ther mal conductivity and specific heat are being investigated. Preliminary results reveal that the thermal diffusivity of polypyrrole is higher than that achieved with traditional polymers. The nature of contacts and junctions with polypyrrole and poly(3-methyl thiophene) are discussed. High work function metals form ohmic junctions with polypyr role while aluminium forms a Schottky barrier with poly(3-methylthiophene). Micro wave studies on polypyrrole films reveal that the microwave transmission and reflection are dependent upon the doping level of the film. Applications of the conducting polymers in data security modules and for light weight electrically conducting wires are also il lustrated.
Publisher: Elsevier BV
Date: 07-2009
Publisher: Elsevier BV
Date: 05-2007
Publisher: IOP Publishing
Date: 10-02-2015
Publisher: Elsevier BV
Date: 07-2004
Publisher: MDPI AG
Date: 15-07-2020
Abstract: Recent advances in fabrication techniques have enabled the production of different types of polymer sensors and actuators that can be utilized in a wide range of applications, such as soft robotics, biomedical, smart textiles and energy harvesting [...]
Publisher: IEEE
Date: 11-2016
Publisher: Informa UK Limited
Date: 30-09-2001
DOI: 10.1081/MA-100105964
Publisher: Informa UK Limited
Date: 20-03-2017
Publisher: IEEE
Date: 10-2009
Publisher: IEEE
Date: 08-2014
Publisher: Elsevier BV
Date: 2011
Publisher: MDPI AG
Date: 02-02-2020
Abstract: Three-dimensional (3D)-printed parts are an essential subcategory of additive manufacturing with the recent proliferation of research in this area. However, 3D-printed parts fabricated by different techniques differ in terms of microstructure and material properties. Catastrophic failures often occur due to unstable crack propagations and therefore a study of fracture behavior of 3D-printed components is a vital component of engineering design. In this paper, experimental tests and numerical studies of fracture modes are presented. A series of experiments were performed on 3D-printed nylon s les made by fused deposition modeling (FDM) and multi-jet fusion (MJF) to determine the load-carrying capacity of U-notched plates fabricated by two different 3D printing techniques. The equivalent material concept (EMC) was used in conjunction with the J-integral failure criterion to investigate the failure of the notched s les. Numerical simulations indicated that when EMC was combined with the J-integral criterion the experimental results could be predicted successfully for the 3D-printed polymer s les.
Publisher: Elsevier BV
Date: 09-2007
Publisher: Elsevier BV
Date: 11-2006
Publisher: IEEE
Date: 05-2011
Publisher: IOP Publishing
Date: 20-12-2018
Publisher: Elsevier BV
Date: 10-2005
Publisher: Springer Science and Business Media LLC
Date: 10-2009
Publisher: IEEE
Date: 05-2011
Publisher: Elsevier BV
Date: 06-2005
Publisher: IEEE
Date: 06-2014
Publisher: MDPI AG
Date: 26-07-2019
DOI: 10.3390/MA12152380
Abstract: Stimuli-responsive polymer systems can be defined as functional materials that show physical or chemical property changes in response to external stimuli, such as temperature, radiation, chemical agents, pH, mechanical stress, and electric and magnetic fields [...]
Publisher: Elsevier BV
Date: 04-2005
Publisher: Elsevier BV
Date: 11-1993
Publisher: MDPI AG
Date: 24-01-2021
DOI: 10.3390/MA14030550
Abstract: The inhomogeneity of the resistance of conducting polypyrrole-coated nylon–Lycra and polyester (PET) fabrics and its effects on surface temperature were investigated through a systematic experimental and numerical work including the optimization of coating conditions to determine the lowest resistivity conductive fabrics and establish a correlation between the fabrication conditions and the efficiency and uniformity of Joule heating in conductive textiles. For this purpose, the effects of plasma pre-treatment and molar concentration analysis of the dopant anthraquinone sulfonic acid (AQSA), oxidant ferric chloride, and monomer pyrrole was carried out to establish the conditions to determine the s le with the lowest electrical resistance for generating heat and model the experiments using the finite element modeling (FEM). Both PET and nylon-Lycra underwent atmospheric plasma treatment to functionalize the fabric surface to improve the binding of the polymer and obtain coatings with reduced resistance. Both fabrics were compared in terms of average electrical resistance for both plasma treated and untreated s les. The plasma treatment induced deep black coatings with lower resistance. Then, heat-generating experiments were conducted on the polypyrrole (PPy) coated fabrics with the lowest resistance using a variable power supply to study the distribution and maximum value of the temperature. The joule heating model was developed to predict the heating of the conductive fabrics via finite element analysis. The model was based on the measured electrical resistance at different zones of the coated fabrics. It was shown that, when the fabric was backed with neoprene insulation, it would heat up quicker and more evenly. The average electrical resistance of the PPy-PET s le used was 190 Ω, and a maximum temperature reading of 43 °C was recorded. The model results exhibited good agreement with thermal camera data.
Publisher: Elsevier BV
Date: 05-2005
Publisher: IEEE
Date: 11-2017
Publisher: IEEE
Date: 08-2012
Publisher: Elsevier BV
Date: 09-2014
Publisher: Elsevier BV
Date: 10-1996
Publisher: Informa UK Limited
Date: 03-08-2020
Publisher: Trans Tech Publications, Ltd.
Date: 06-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.654-656.2467
Abstract: Electrochemical synthesis of a tri-layer polypyrrole based actuator optimized for performance was reported. The 0.05 M pyrrole and 0.05 M tetrabutylammonium hexaflurophosphate in propylene carbonate (PC) yielded the optimum performance and stability. The force produced ranged from 0.2 to 0.4mN. Cyclic deflection tests on PC based actuators for 3 hours indicated that the displacement decreased by 60%. PC based actuator had a longer operating time, exceeding 3 hours, compared to acetonitrile based actuators. A triple-layer model of the polymer actuator was developed based on the classic bending beam theory by considering strain electrode material. A tri-layer actuator was fabricated [4, 6], by initially sputter coating a PVDF film with approximately 100nm of gold layer, resulting in a conductive film with a surface resistance of 8-10Ω. The PVDF film was about ~145µm thick had an approximate pore size of 45μm. A solution containing 0.05M distilled pyrrole monomer, 0.05M (TBAPF6) and 1% (w/w) distilled water in PC (propylene carbonate) solution was purged with nitrogen for 15 minutes. The continuity between PPy and PVDF. Results predicted by the model were in good agreement with the experimental data.
Publisher: Elsevier BV
Date: 2008
Publisher: Springer Science and Business Media LLC
Date: 1994
DOI: 10.1007/BF00633533
Publisher: Elsevier BV
Date: 11-2007
Publisher: Springer Science and Business Media LLC
Date: 06-1993
DOI: 10.1007/BF00354252
Publisher: Springer Science and Business Media LLC
Date: 02-2012
Publisher: MDPI AG
Date: 21-05-2021
DOI: 10.3390/S21113574
Abstract: Electroconductive hydrogels with stimuli-free self-healing and self-recovery (SELF) properties and high mechanical strength for wearable strain sensors is an area of intensive research activity at the moment. Most electroconductive hydrogels, however, consist of static bonds for mechanical strength and dynamic bonds for SELF performance, presenting a challenge to improve both properties into one single hydrogel. An alternative strategy to successfully incorporate both properties into one system is via the use of stiff or rigid, yet dynamic nano-materials. In this work, a nano-hybrid modifier derived from nano-chitin coated with ferric ions and tannic acid (TA/Fe@ChNFs) is blended into a starch olyvinyl alcohol olyacrylic acid (St/PVA/PAA) hydrogel. It is hypothesized that the TA/Fe@ChNFs nanohybrid imparts both mechanical strength and stimuli-free SELF properties to the hydrogel via dynamic catecholato-metal coordination bonds. Additionally, the catechol groups of TA provide mussel-inspired adhesion properties to the hydrogel. Due to its electroconductivity, toughness, stimuli-free SELF properties, and self-adhesiveness, a prototype soft wearable strain sensor is created using this hydrogel and subsequently tested.
Publisher: Elsevier BV
Date: 2009
Publisher: MDPI AG
Date: 28-05-2020
Abstract: Functional polymers show unique physical and chemical properties, which can manifest as dynamic responses to external stimuli such as radiation, temperature, chemical reaction, external force, and magnetic and electric fields [...]
Publisher: IEEE
Date: 12-2011
Publisher: Springer Science and Business Media LLC
Date: 09-2005
DOI: 10.1007/BF02875651
Publisher: Wiley
Date: 12-05-2003
DOI: 10.1002/PI.1195
Publisher: IEEE
Date: 07-2010
Publisher: IEEE
Date: 07-2010
Publisher: Mary Ann Liebert Inc
Date: 06-2016
Publisher: SAGE Publications
Date: 09-1994
DOI: 10.1177/1045389X9400500501
Abstract: There are over 100 conducting polymers which have been synthesised by chemists with a wide range of specific electrical conductivities. Many of these polymers are suitable for elec tronic device fabrication. Semi-conducting and conducting polymers have potential for application in several areas. In this paper electronic and microwave properties are explored. Fabrication of elec tronic and microwave devices can be achieved with these special polymers which are not possible with say silicon or gallium arsenide. Wide area flexible electronic junctions can be fabricated. Polymers have low density, hence conductivity to weight ratio can be higher than metals. Optical transparency together with electrical conduction has been achieved. This article presents an overview of the results of investigations undertaken within the Centre for Materials Technology (CMT) in this area over the past 4 years. This includes work on monomer and polymer synthesis, molecular structure-property relationships, electromagnetic shielding, thermal, optical and junction properties.
Publisher: Elsevier BV
Date: 04-2000
Publisher: Informa UK Limited
Date: 04-2006
Publisher: Wiley
Date: 11-09-2012
Location: Australia
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
No related grants have been discovered for Akif Kaynak.