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Fulltext An Aligned-Gap and Centered-Gap Rectangular Multiple Split Ring Resonator for dielectric sensing applications

Rusni IM, Ismail A, Alhawari AR, Hamidon MN, Yusof NA

Sensors (Basel), 2014 Jul 21;14(7):13134-48.
PMID: 25051036 DOI: 10.3390/s140713134

This paper presents the design and development of a planar Aligned-Gap and Centered-Gap Rectangular Multiple Split Ring Resonator (SRR) for microwave sensors that operates at a resonance frequency around 5 GHz. The sensor consists of a microstrip transmission line loaded with two elements of rectangular SRR on both sides. The proposed metamaterial sensors were designed and fabricated on Rogers RT5880 substrate having dielectric constant of 2.2 and thickness of 0.787 mm. The final dimension of the proposed sensor was measured at 35 × 14 mm2. Measured results show good agreement with simulated ones as well as exhibiting high Q-factor for use in sensing application. A remarkably shift of resonance frequency is observed upon introduction of several sample with different dielectric value.

Matched MeSH terms: Equipment Design/instrumentation*
Fulltext Hardware implementation of 32-bit high-speed direct digital frequency synthesizer

Ibrahim SH, Ali SH, Islam MS

ScientificWorldJournal, 2014;2014:131568.
PMID: 24991635 DOI: 10.1155/2014/131568

The design and implementation of a high-speed direct digital frequency synthesizer are presented. A modified Brent-Kung parallel adder is combined with pipelining technique to improve the speed of the system. A gated clock technique is proposed to reduce the number of registers in the phase accumulator design. The quarter wave symmetry technique is used to store only one quarter of the sine wave. The ROM lookup table (LUT) is partitioned into three 4-bit sub-ROMs based on angular decomposition technique and trigonometric identity. Exploiting the advantages of sine-cosine symmetrical attributes together with XOR logic gates, one sub-ROM block can be removed from the design. These techniques, compressed the ROM into 368 bits. The ROM compressed ratio is 534.2:1, with only two adders, two multipliers, and XOR-gates with high frequency resolution of 0.029 Hz. These techniques make the direct digital frequency synthesizer an attractive candidate for wireless communication applications.

Matched MeSH terms: Equipment Design/instrumentation*
Fulltext Design of a Miniaturized Meandered Line Antenna for UHF RFID Tags

Rokunuzzaman M, Islam MT, Rowe WS, Kibria S, Jit Singh M, Misran N

PLoS One, 2016;11(8):e0161293.
PMID: 27533470 DOI: 10.1371/journal.pone.0161293

A semi-circle looped vertically omnidirectional radiation (VOR) patterned tag antenna for UHF (919-923 MHz for Malaysia) frequency is designed to overcome the impedance mismatch issue in this paper. Two impedance matching feeding strips are used in the antenna structure to tune the input impedance of the antenna. Two dipole shaped meandered lines are used to achieve a VOR pattern. The proposed antenna is designed for 23-j224 Ω chip impedance. The antenna is suitable for 'place and tag' application. A small size of 77.68×35.5 mm2 is achieved for a read range performance of 8.3 meters using Malaysia regulated maximum power transfer of 2.0 W effective radiated power (ERP).

Matched MeSH terms: Equipment Design/instrumentation*
Fulltext Review of development survey of phase change material models in building applications

Akeiber HJ, Wahid MA, Hussen HM, Mohammad AT

ScientificWorldJournal, 2014;2014:391690.
PMID: 25313367 DOI: 10.1155/2014/391690

The application of phase change materials (PCMs) in green buildings has been increasing rapidly. PCM applications in green buildings include several development models. This paper briefly surveys the recent research and development activities of PCM technology in building applications. Firstly, a basic description of phase change and their principles is provided; the classification and applications of PCMs are also included. Secondly, PCM models in buildings are reviewed and discussed according to the wall, roof, floor, and cooling systems. Finally, conclusions are presented based on the collected data.

Matched MeSH terms: Equipment Design/instrumentation
Fulltext Wireless displacement sensing of micromachined spiral-coil actuator using resonant frequency tracking

Ali MS, AbuZaiter A, Schlosser C, Bycraft B, Takahata K

Sensors (Basel), 2014 Jul 10;14(7):12399-409.
PMID: 25014100 DOI: 10.3390/s140712399

This paper reports a method that enables real-time displacement monitoring and control of micromachined resonant-type actuators using wireless radiofrequency (RF). The method is applied to an out-of-plane, spiral-coil microactuator based on shape-memory-alloy (SMA). The SMA spiral coil forms an inductor-capacitor resonant circuit that is excited using external RF magnetic fields to thermally actuate the coil. The actuation causes a shift in the circuit's resonance as the coil is displaced vertically, which is wirelessly monitored through an external antenna to track the displacements. Controlled actuation and displacement monitoring using the developed method is demonstrated with the microfabricated device. The device exhibits a frequency sensitivity to displacement of 10 kHz/µm or more for a full out-of-plane travel range of 466 µm and an average actuation velocity of up to 155 µm/s. The method described permits the actuator to have a self-sensing function that is passively operated, thereby eliminating the need for separate sensors and batteries on the device, thus realizing precise control while attaining a high level of miniaturization in the device.

Matched MeSH terms: Equipment Design/instrumentation
Fulltext Design of high speed and low offset dynamic latch comparator in 0.18 µm CMOS process

Rahman LF, Reaz MB, Yin CC, Ali MA, Marufuzzaman M

PLoS One, 2014;9(10):e108634.
PMID: 25299266 DOI: 10.1371/journal.pone.0108634

The cross-coupled circuit mechanism based dynamic latch comparator is presented in this research. The comparator is designed using differential input stages with regenerative S-R latch to achieve lower offset, lower power, higher speed and higher resolution. In order to decrease circuit complexity, a comparator should maintain power, speed, resolution and offset-voltage properly. Simulations show that this novel dynamic latch comparator designed in 0.18 µm CMOS technology achieves 3.44 mV resolution with 8 bit precision at a frequency of 50 MHz while dissipating 158.5 µW from 1.8 V supply and 88.05 µA average current. Moreover, the proposed design propagates as fast as 4.2 nS with energy efficiency of 0.7 fJ/conversion-step. Additionally, the core circuit layout only occupies 0.008 mm2.

Matched MeSH terms: Equipment Design/instrumentation*
Fulltext An improved synchronous reference frame current control strategy for a photovoltaic grid-connected inverter under unbalanced and nonlinear load conditions

Naderipour A, Asuhaimi Mohd Zin A, Bin Habibuddin MH, Miveh MR, Guerrero JM

PLoS One, 2017;12(2):e0164856.
PMID: 28192436 DOI: 10.1371/journal.pone.0164856

In recent years, renewable energy sources have been considered the most encouraging resources for grid and off-grid power generation. This paper presents an improved current control strategy for a three-phase photovoltaic grid-connected inverter (GCI) under unbalanced and nonlinear load conditions. It is challenging to suppress the harmonic content in the output current below a pre-set value in the GCI. It is also difficult to compensate for unbalanced loads even when the grid is under disruption due to total harmonic distortion (THD) and unbalanced loads. The primary advantage and objective of this method is to effectively compensate for the harmonic current content of the grid current and microgrid without the use of any compensation devices, such as active and passive filters. This method leads to a very low THD in both the GCI currents and the current exchanged with the grid. The control approach is designed to control the active and reactive power and harmonic current compensation, and it also corrects the system unbalance. The proposed control method features the synchronous reference frame (SRF) method. Simulation results are presented to demonstrate the effective performance of the proposed method.

Matched MeSH terms: Equipment Design/instrumentation*
Novel Multipin Electrode Cap System for Dry Electroencephalography

Fiedler P, Pedrosa P, Griebel S, Fonseca C, Vaz F, Supriyanto E, et al.

Brain Topogr, 2015 Sep;28(5):647-656.
PMID: 25998854 DOI: 10.1007/s10548-015-0435-5

Current usage of electroencephalography (EEG) is limited to laboratory environments. Self-application of a multichannel wet EEG caps is practically impossible, since the application of state-of-the-art wet EEG sensors requires trained laboratory staff. We propose a novel EEG cap system with multipin dry electrodes overcoming this problem. We describe the design of a novel 24-pin dry electrode made from polyurethane and coated with Ag/AgCl. A textile cap system holds 97 of these dry electrodes. An EEG study with 20 volunteers compares the 97-channel dry EEG cap with a conventional 128-channel wet EEG cap for resting state EEG, alpha activity, eye blink artifacts and checkerboard pattern reversal visual evoked potentials. All volunteers report a good cap fit and good wearing comfort. Average impedances are below 150 kΩ for 92 out of 97 dry electrodes, enabling recording with standard EEG amplifiers. No significant differences are observed between wet and dry power spectral densities for all EEG bands. No significant differences are observed between the wet and dry global field power time courses of visual evoked potentials. The 2D interpolated topographic maps show significant differences of 3.52 and 0.44% of the map areas for the N75 and N145 VEP components, respectively. For the P100 component, no significant differences are observed. Dry multipin electrodes integrated in a textile EEG cap overcome the principle limitations of wet electrodes, allow rapid application of EEG multichannel caps by non-trained persons, and thus enable new fields of application for multichannel EEG acquisition.

Matched MeSH terms: Equipment Design/instrumentation*
Development of new hard hat dimensions using user-centered design approach among oil palm harvesters

Mohd Shukoor NS, Mohd Tamrin SB, Guan NY, Mohd Suadi Nata DH

Work, 2018;60(1):129-134.
PMID: 29843301 DOI: 10.3233/WOR-182741

BACKGROUND: Hard hats are among the personal protective equipment (PPE) used in many industries to reduce the impact of any falling object on the skull and also to prevent head and brain injuries. However, the practice of wearing a safety helmet during working hours is still low. This is due to the physical discomfort perceived by safety helmet users.
OBJECTIVE: Given the unpopularity of the current hard hat, the general perception of workers concerning its use and its measurements are the determining factors in the development of a new hard hat.
METHOD: A cross-sectional study was conducted in which 132 male oil palm harvesters between 19 and 60 years of age were selected from among the employees of the same oil palm harvesting company. A set of questionnaires was developed to collect their socio-demographic information as well as their perceptions of comfort and the prevalence of head injury. In addition, a set of measuring instruments, including Martin's anthropometry set, was used for head measurement and data collection in respect of the current hard hat. In this research, six respondents were randomly selected to attend an interview session for qualitative assessment.RESULTSBased on the questionnaires, the unpopularity in the use of the hard hat was largely influenced by factors related to poor design, in general, and, specifically, poor ventilation (64%), load (67% ), and physical discomfort (42% ). The measurements of the anthropometric parameters and the dimensions of the hard hat also showed a significant mismatch.
CONCLUSION: The unpopularity of the current hard hat among oil palm harvesters stemmed from the discomfort from wearing, which showed that the development of a new hard hat could lead to better usage and the greater likelihood of wearing a hard hat throughout the working day.

Matched MeSH terms: Equipment Design/instrumentation