5,834 research outputs found
Developing a framework of non-fatal occupational injury surveillance for risk control in palm oil mills
Non-fatal occupational injury (NFOI) and its risk factors have become a current global
concern. The need of research towards the relationship between occupational injury
and its risk factor is essential, to fulfil the purpose and setting the priority of
implementing safety preventive approaches at workplace. This research intended to
develop a framework of NFOI surveillance by using epidemiological data, noise
exposure data and NFOI data among palm oil mills’ workers. A total of 420
respondents who assigned in operation and processing areas (OP) (n=333) and general
or office workers (n=87) had voluntary participated in this research. A questionnaire
session with respondents was held to obtain epidemiological data and NFOI
information via validated questionnaire. Noise hazard monitoring was executed by
using Sound Level Meter (SLM) for environmental noise monitoring and Personal
Sound Dosimeter for personal noise monitoring. Gathered data were analysed in
quantitative method by using statistical software IBM SPSS Statistic version 21 and a
risk matrix table for injury risk rating evaluation. It was discovered that high noise
exposure level (≥ 85 dB[A]) was significantly associated with non-fatal occupational
injury among OP workers (φ=0.123, p<0.05) with OR=1.87 (95% CI, 1.080-3.235,
p<0.05). Risk rating for reported NFOI was at moderate level, with minor cuts and
scratches were the dominant type of injury (42.6%). Analysis of logistic regression
indicated that working in shift, not wearing protective gloves, health problems such as
shortness of breath and ringing in ears, and excessive noise level (≥ 85 dB[A]) were
the risk factors of NFOI in palm oil mills among OP workers. A framework of nonfatal
injury surveillance in palm oil mills was developed based on the findings with
integration of risk management process and injury prevention principles. This
framework is anticipated to help the management in decision making for preventive
actions and early detection of occupational health effects among workers
Distributed Integrated Circuits: An Alternative Approach to High-Frequency Design
Distributed integrated circuits are presented as a methodology to design high-frequency communication building blocks. Distributed circuits operate based on multiple parallel signal paths working in synchronization that can be used to enhance the frequency of operation, combine power, and enhance the robustness of the design. These multiple signal paths usually result in strong couplings inside the circuit that necessitate
a treatment spanning architecture, circuits, devices, and electromagnetic levels of abstraction
Design of A Low Power Low Voltage CMOS Opamp
In this paper a CMOS operational amplifier is presented which operates at 2V
power supply and 1microA input bias current at 0.8 micron technology using non
conventional mode of operation of MOS transistors and whose input is depended
on bias current. The unique behaviour of the MOS transistors in subthreshold
region not only allows a designer to work at low input bias current but also at
low voltage. While operating the device at weak inversion results low power
dissipation but dynamic range is degraded. Optimum balance between power
dissipation and dynamic range results when the MOS transistors are operated at
moderate inversion. Power is again minimised by the application of input
dependant bias current using feedback loops in the input transistors of the
differential pair with two current substractors. In comparison with the
reported low power low voltage opamps at 0.8 micron technology, this opamp has
very low standby power consumption with a high driving capability and operates
at low voltage. The opamp is fairly small (0.0084 mm 2) and slew rate is more
than other low power low voltage opamps reported at 0.8 um technology [1,2].
Vittoz at al [3] reported that slew rate can be improved by adaptive biasing
technique and power dissipation can be reduced by operating the device in weak
inversion. Though lower power dissipation is achieved the area required by the
circuit is very large and speed is too small. So, operating the device in
moderate inversion is a good solution. Also operating the device in
subthreshold region not only allows lower power dissipation but also a lower
voltage operation is achieved.Comment: 8 Pages, VLSICS Journa
Novel active function blocks and their applications in frequency filters and quadrature oscillators
Kmitočtové filtry a sinusoidní oscilátory jsou lineární elektronické obvody, které jsou používány v široké oblasti elektroniky a jsou základními stavebními bloky v analogovém zpracování signálu. V poslední dekádě pro tento účel bylo prezentováno velké množství stavebních funkčních bloků. V letech 2000 a 2006 na Ústavu telekomunikací, VUT v Brně byly definovány univerzální proudový konvejor (UCC) a univerzální napět'ový konvejor (UVC) a vyrobeny ve spolupráci s firmou AMI Semiconductor Czech, Ltd. Ovšem, stále existuje požadavek na vývoj nových aktivních prvků, které nabízejí nové výhody. Hlavní přínos práce proto spočívá v definici dalších původních aktivních stavebních bloků jako jsou differential-input buffered and transconductance amplifier (DBTA), current follower transconductance amplifier (CFTA), z-copy current-controlled current inverting transconductance amplifier (ZC-CCCITA), generalized current follower differential input transconductance amplifier (GCFDITA), voltage gain-controlled modified current-feedback operational amplifier (VGC-MCFOA), a minus-type current-controlled third-generation voltage conveyor (CC-VCIII-). Pomocí navržených aktivních stavebních bloků byly prezentovány původní zapojení fázovacích článků prvního řádu, univerzální filtry druhého řádu, ekvivalenty obvodu typu KHN, inverzní filtry, aktivní simulátory uzemněného induktoru a kvadraturní sinusoidní oscilátory pracující v proudovém, napět'ovém a smíšeném módu. Chování navržených obvodů byla ověřena simulací v prostředí SPICE a ve vybraných případech experimentálním měřením.Frequency filters and sinusoidal oscillators are linear electric circuits that are used in wide area of electronics and also are the basic building blocks in analogue signal processing. In the last decade, huge number of active building blocks (ABBs) were presented for this purpose. In 2000 and 2006, the universal current conveyor (UCC) and the universal voltage conveyor (UVC), respectively, were designed at the Department of Telecommunication, BUT, Brno, and produced in cooperation with AMI Semiconductor Czech, Ltd. There is still the need to develop new active elements that offer new advantages. The main contribution of this thesis is, therefore, the definition of other novel ABBs such as the differential-input buffered and transconductance amplifier (DBTA), the current follower transconductance amplifier (CFTA), the z-copy current-controlled current inverting transconductance amplifier (ZC-CCCITA), the generalized current follower differential input transconductance amplifier (GCFDITA), the voltage gain-controlled modified current-feedback operational amplifier (VGC-MCFOA), and the minus-type current-controlled third-generation voltage conveyor (CC-VCIII-). Using the proposed ABBs, novel structures of first-order all-pass filters, second-order universal filters, KHN-equivalent circuits, inverse filters, active grounded inductance simulators, and quadrature sinusoidal oscillators working in the current-, voltage-, or mixed-mode are presented. The behavior of the proposed circuits has been verified by SPICE simulations and in selected cases also by experimental measurements.
High Gain Amplifier with Enhanced Cascoded Compensation
A two-stage CMOS operational amplifier with both, gain-boosting and indirect current feedback frequency compensation performed by means of regulated cascode amplifiers, is presented. By using quasi-floating-gate transistors (QFGT) the supply requirements, the number of capacitors and the size of the compensation capacitors respect to other Miller schemes are reduced. A prototype was fabricated using a 0.5 μm technology, resulting, for a load of 45 pF and supply voltage of 1.65 V, in open-loop-gain of 129 dB, 23 MHz of gain-bandwidth product, 60o phase margin, 675 μW power consumption and 1% settling time of 28 ns
A Survey of Non-conventional Techniques for Low-voltage Low-power Analog Circuit Design
Designing integrated circuits able to work under low-voltage (LV) low-power (LP) condition is currently undergoing a very considerable boom. Reducing voltage supply and power consumption of integrated circuits is crucial factor since in general it ensures the device reliability, prevents overheating of the circuits and in particular prolongs the operation period for battery powered devices. Recently, non-conventional techniques i.e. bulk-driven (BD), floating-gate (FG) and quasi-floating-gate (QFG) techniques have been proposed as powerful ways to reduce the design complexity and push the voltage supply towards threshold voltage of the MOS transistors (MOST). Therefore, this paper presents the operation principle, the advantages and disadvantages of each of these techniques, enabling circuit designers to choose the proper design technique based on application requirements. As an example of application three operational transconductance amplifiers (OTA) base on these non-conventional techniques are presented, the voltage supply is only ±0.4 V and the power consumption is 23.5 µW. PSpice simulation results using the 0.18 µm CMOS technology from TSMC are included to verify the design functionality and correspondence with theory
Low-Voltage Ultra-Low-Power Current Conveyor Based on Quasi-Floating Gate Transistors
The field of low-voltage low-power CMOS technology has grown rapidly in recent years; it is an essential prerequisite particularly for portable electronic equipment and implantable medical devices due to its influence on battery lifetime. Recently, significant improvements in implementing circuits working in the low-voltage low-power area have been achieved, but circuit designers face severe challenges when trying to improve or even maintain the circuit performance with reduced supply voltage. In this paper, a low-voltage ultra-low-power current conveyor second generation CCII based on quasi-floating gate transistors is presented. The proposed circuit operates at a very low supply voltage of only ±0.4 V with rail-to-rail voltage swing capability and a total quiescent power consumption of mere 9.5 µW. Further, the proposed circuit is not only able to process the AC signal as it's usual at quasi-floating gate transistors but also the DC which extends the applicability of the proposed circuit. In conclusion, an application example of the current-mode quadrature oscillator is presented. PSpice simulation results using the 0.18 µm TSMC CMOS technology are included to confirm the attractive properties of the proposed circuit
Assessment of ecosystem integrity of lowland dipterocarp forest ecosystem using remote sensing
Ecosystem Integrity Index (EII) is a concept to determine the quality or the health of an ecosystem. The EII development can assist forest managers and decision makers in the conservation effort and forest management in Malaysia through the development of a simple and easy-to-adopt index. The aim of this study is to assess and evaluate the EII through the development of forest structure empirical models from remotely sensed data for lowland dipterocarp forest in Malaysia. The objectives of this study are: (i) to assess the structure and composition of lowland dipterocarp forest in Malaysia, (ii) to develop empirical model for estimating stand structure from remotely sensed data, and (iii) to derive the ecosystem integrity index for lowland dipterocarp forest. Tree Basal Area (BA), aboveground biomass (AGB) and volume plot from plot data were used as dependent variables, while remote sensing data from Landsat, Pleiades and LiDAR were used as independent variables for model development. Tree plot census was carried out from 17 to 19 May 2016, while remote sensing data acquisition dates for Landsat, Pleiades and LiDAR were 13 March 2016, 24 January 2015 and April 2015 respectively. Forest Structure Modeling was carried out by means of a correlation analysis with the calibration of dependent and independent data to select the most significant and accurate remote sensing variables to derive empiric equation (model), fitting stage to select the best model with the highest coefficient of determination (R2) and the lowest root mean square error ( RMSE) validation of the final selected. The Ecosystem Integrity Index was developed by the average percentage of the predicted BA, AGB and model volume. The EII was categorised at five integrity levels as high (81–100%), medium high (61–80%), moderate (41–60%), medium low (21–40%) and low (0–20%). A total of 1035 trees with diameter at breast height (DBH) of 5.0 cm and above were recorded in 69.115 ha sampling areas. The total trees recorded represented 150 species from 87 genera and 34 families. Shorea macroptera (Dipterocarpaceae), S. leprosula (Dipterocarpaceae) and S. parviflora (Dipterocarpaceae) are three dominant species, with Species Important Value Index (SIVi) of 6.49%, 6.23% and 5.51%, respectively. Dipterocarpaceae is the most dominant with Family Important Value Index (FIVi) of 33.54%. The developed final model is robust and consistent with high R2 with range of 0.84 to 0.87. The final models constructed for AGB, BA and volume value of R2 are 0.85, 0.84 and 0.87 respectively. The RMSE of AGB, BA and volume model are 53.1 Mg/ha, 3.54 m2/ha and 46.4 m3/ha, respectively. The overall stand AGB, BA and volume for Sungai Menyala Forest Reserve is 282.29 Mg/ha, 17.68 m2/ha and 239.51 m3/ha. An Ecosystem Integrity Index (EII) assessment has been successfully demonstrated by this study with production of practical, multi-scaled, flexible, adjustable and policy-relevant index. The overall EII of Sungai Menyala Forest Reserve is in Category 3, which shows that the area is within the medium value
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