• Title/Summary/Keyword: V/F Control

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Freeze-thaw resistance and sorptivity of self-compacting mortar with ternary blends

  • Turk, Kazim;Kina, Ceren
    • Computers and Concrete
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    • v.21 no.2
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    • pp.149-156
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    • 2018
  • This paper investigated the influence of binary and ternary blends of mineral admixtures in self-compacted mortar (SCM) on the fresh, mechanical and durability properties. For this purpose, 25 mortar mixtures were prepared having a total binder content of $640kg/cm^3$ and water/binder ratio between 0.41 and 0.50. All the mixtures consisted of Portland cement (PC), fly ash (FA) and silica fume (SF) as binary and ternary blends and air-entrained admixture wasn't used while control mixture contained only PC. The compressive and tensile strength tests were conducted for 28 and 91 days as well as slump-flow and V-funnel time tests whilst freeze-thaw (F-T) resistance and capillary water absorption tests were made for 91-day. Finally, in general, the use of SF with FA as ternary blends improved the tensile strength of mortars at 28- and 91-day while the use of SF15 with FA increased the compressive strength of the mortars compared to binary blends of FA. SCM mixtures with ternary blends had lower the sorptivity values than that of the mortars with binary blends of FA and the control mixture due to the beneficial properties of SF while the use of FA with SF as ternary blends induced the F-T resistance enhancement.

The Yield and Composition of Milk from Transgenic Rabbits

  • Chrenek, P.;Chrastinova, L.;Kirchnerova, K.;Makarevich, A.V.;Foltys, V.
    • Asian-Australasian Journal of Animal Sciences
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    • v.20 no.4
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    • pp.482-486
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    • 2007
  • Basic objective of this research was to compare the milk yield and composition of New Zealand White transgenic rabbit females expressing recombinant human factor VIII (hFVIII) in mammary gland during lactation with that of non-transgenic rabbit females of the same age during 30 days of lactation. Transgenic founders were generated by the microinjection of foreign DNA (mWAP-hFVIII gene construct) into the egg. F1, F2 and F3 generations of transgenic rabbits were obtained after mating of transgenic founder rabbits with non-transgenic rabbits. The amount of milk rejected was measured by weight-suckle-weight method at $10^{th}$, $20^{th}$and $30^{th}$ day of lactation. Quality of milk (content of fat, protein, lactose, dry ash, and some minerals) from transgenic and non-transgenic rabbit was also determined. Comparison of milk yield, determined by weight-suckle-weight method, showed significantly higher (p<0.05) milk production at day 20 of first lactation in non-transgenic females, but on the same day of second lactation higher milk yield was measured in transgenic ones. Significantly higher (p<0.05) content of milk fat and protein was determined in transgenic milk whilst higher content of lactose was found in non-transgenic milk. The content of minerals (calcium, phosphorus, magnesium and sodium) did not differ in both experimental and control groups. Our results showed that milk yield and composition of transgenic rabbit females (mammary specific transgenic over-expression of hFVIII) over several generations is only slightly and transiently different from milk yield of non-transgenic females, which had no significant consequence on the litter size and viability.

Effects of concentrations and types of neutral salts on the foaming properties of sodium caseinate (중성염의 종류 및 농도가 sodium caseinate의 거품성에 미치는 영향)

  • Yang, Seung-Taek;Park, Hyung-Sun
    • Applied Biological Chemistry
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    • v.36 no.6
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    • pp.434-439
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    • 1993
  • To investigate the effects of neutral salts on the foaming properties of sodium caseinate, turbidity, surface tension, absolute viscosity, foaming ability and foam stability of the caseinate solutions(5%, w/v) with added NaF, $Na_2SO_4$, NaCl, $NaNO_3$, and NaSCN at concentrations of 0.1, 0.5, 1.0, 1.5 and 2.0 M were examined. NaCl and $NaNO_3$ improved the foaming ability compared to sodium caseinate without salt, and also $Na_2SO_4$ and NaF did the foaming ability at the concentrations of 0.1M and 0.5M, while NaSCN did not improve the foaming ability. For foaming ability optimal concentrations of the salts were 0.5, 1.5, and 1.0 M in $Na_2SO_4$, NaCl, and NaSCN, respectively. Additions of $Na_2SO_4$, NaF and $NaNO_3$ at 0.5 M concentrations improved the foam stability of sodium caseinate by 825%, 615%, and 53% compared to control, while those of NaSCN reduced foam stability.

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Design of a 12b SAR ADC for DMPPT Control in a Photovoltaic System

  • Rho, Sung-Chan;Lim, Shin-Il
    • IEIE Transactions on Smart Processing and Computing
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    • v.4 no.3
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    • pp.189-193
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    • 2015
  • This paper provides the design techniques of a successive approximation register (SAR) type 12b analog-to-digital converter (ADC) for distributed maximum power point tracking (DMPPT) control in a photovoltaic system. Both a top-plate sampling technique and a $V_{CM}$-based switching technique are applied to the 12b capacitor digital-to-analog converter (CDAC). With these techniques, we can implement a 12b SAR ADC with a 10b capacitor array digital-to-analog converter (DAC). To enhance the accuracy of the ADC, a single-to-differential converted DAC is exploited with the dual sampling technique during top-plate sampling. Simulation results show that the proposed ADC can achieve a signal-to-noise plus distortion ratio (SNDR) of 70.8dB, a spurious free dynamic range (SFDR) of 83.3dB and an effective number of bits (ENOB) of 11.5b with bipolar CMOS LDMOD (BCDMOS) $0.35{\mu}m$ technology. Total power consumption is 115uW under a supply voltage of 3.3V at a sampling frequency of 1.25MHz. And the figure of merit (FoM) is 32.68fJ/conversion-step.

Dependence of Blue Organic Emitter Layer Thickness to Optical Property of 2-wavelength White Organic Light-emitting Diodes (청색 유기발광층 두께에 따른 2-파장 방식의 백색 유기발광 소자의 광학적 특성)

  • Park, Chan-Jun;Cho, Nam-Ihn;Song, Young-Wook
    • Journal of Institute of Control, Robotics and Systems
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    • v.14 no.6
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    • pp.511-514
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    • 2008
  • 2-wavelength type white OLED devices have been made consisted of two layers; a layer with blue light emitting DPVBi host and other EML layer with yellow emitting rubrene dopant. New method to get white emitting device has been suggested by varying thicknesses of the DPVBi layer. The ITO/2-TNATA($150{\AA}$)/NPB($350{\AA}$)/DPVBi($35{\AA}$)/DPVBi:rubrene (2wt%,$200{\AA}$)/DPVBi($100{\AA}$)/Alq_3($50{\AA}$)/LiF($5{\AA}$)/Al($1000{\AA}$) structure has showed optimum results in CIE coordinates of (0.3233, 0.33). OLED devices with this structure has properties of $1.2d/m^2$ at turn-on voltage of 3.9V and $1037cd/m^2$ at 7.9V. This structure has advantages of simple fabrication and easy to emit the white color.

Frequency Dependent Properties of Tris(8-Hydroxyquinoline) Aluminum Thin Films

  • Lee, Yong-Soo;Park, Jae-Hoon;Choi, Jong-Sun
    • KIEE International Transactions on Electrophysics and Applications
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    • v.11C no.3
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    • pp.70-74
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    • 2001
  • Admittance or impedance spectroscopy is one of the powerful tools to study dielectric relaxation and loss processes in organic and inorganic materials. In this study, the frequency dependent properties of an indium tin oxide/tris(8-hydroxyquinoline) aluminum($Alq_3$)/aluminum structure have been studied. The conductance of the $Alq_3$ film increases with the DC applied voltage up to 4V and decreases above 4V in the low frequency region. This indicates that the resistance of the device decreases with the applied bias due to the carrier injection enhancement, thereafter the injected carriers form the space charge and the additional injection of carriers is prevented. The Cole-Cole plot of the admittance takes a one-semicircle shape, which means that the device can be modeled as a parallel resistor-capacitor network. The resistance and capacitance were estimated as 8.62k${\Omega}$ and 2.7nF, respectively, at 3V in the low frequency region. The dielectric constant ( ${\epsilon}'$ ) of the $Alq_3$ film is independent of the frequency in the low frequency region below 100kHz, while the frequency dependency was observed at above 100kHz. The dielectric loss factor ( ${\epsilon}"$ ) of the $Alq_3$ film shows the dielectric dispersion below 100kHz and dielectric absorption in higher frequency domain. The dispersion is thought to be related to the hopping process of the carriers. The ${\epsilon}"$ is proportional to the reciprocal of the frequency. The dielectric relaxation time was extracted to about 0.318${\mu}s$ from the dielectric absorption spectrum.

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Hybrid Neural Classifier Combined with H-ART2 and F-LVQ for Face Recognition

  • Kim, Do-Hyeon;Cha, Eui-Young;Kim, Kwang-Baek
    • 제어로봇시스템학회:학술대회논문집
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    • 2005.06a
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    • pp.1287-1292
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    • 2005
  • This paper presents an effective pattern classification model by designing an artificial neural network based pattern classifiers for face recognition. First, a RGB image inputted from a frame grabber is converted into a HSV image which is similar to the human beings' vision system. Then, the coarse facial region is extracted using the hue(H) and saturation(S) components except intensity(V) component which is sensitive to the environmental illumination. Next, the fine facial region extraction process is performed by matching with the edge and gray based templates. To make a light-invariant and qualified facial image, histogram equalization and intensity compensation processing using illumination plane are performed. The finally extracted and enhanced facial images are used for training the pattern classification models. The proposed H-ART2 model which has the hierarchical ART2 layers and F-LVQ model which is optimized by fuzzy membership make it possible to classify facial patterns by optimizing relations of clusters and searching clustered reference patterns effectively. Experimental results show that the proposed face recognition system is as good as the SVM model which is famous for face recognition field in recognition rate and even better in classification speed. Moreover high recognition rate could be acquired by combining the proposed neural classification models.

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Effect of Ultrasonic Frequency on the Atomization Characteristics of Single Water Droplet in an Acoustic Levitation Field (음향 부양장(acoustic levitation field)에서 초음파 주파수(ultrasonic frequency)에 따른 단일 액적의 미립화 특성)

  • Suh, Hyun Kyu
    • Journal of ILASS-Korea
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    • v.18 no.3
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    • pp.126-131
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    • 2013
  • This paper describes the effect of ultrasonic frequency(f) on the atomization and deformation characteristics of single water droplet in an acoustic levitation field. To achieve this, the ultrasonic levitator that can control sound pressure and velocity amplitude by changing frequency was installed, and visualization of single water droplet was conducted with high resolution ICCD and CCD camera. At the same time, atomization and deformation characteristics of single water droplet was studied in terms of normalized droplet diameter($d/d_0$), droplet diameter(d) variation and droplet volume(V) variation under different ultrasonic frequency(f) conditions. It was revealed that increase of ultrasonic frequency reduces the droplet diameter. Therefore, it is able to levitate with low sound pressure level. It also induces the wide oscillation range, large diameter and volume variation of water droplet. In conclusion, the increase of ultrasonic frequency(f) can enhance the atomization performance of single water droplet.

Wood and Leaf Litter Decomposition and Nutrient Release from Tectona grandis Linn. f. in a Tropical Dry Deciduous Forest of Rajasthan, Western India

  • Kumar, J.I. Nirmal;Sajish, P.R.;Kumar, Rita.N.;Bhoi, Rohit Kumar
    • Journal of Forest and Environmental Science
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    • v.26 no.1
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    • pp.17-23
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    • 2010
  • The present study was conducted to quantify wood and leaf litter decomposition and nutrient release of a dominant tree species, Tectona grandis Linn. F. in a tropical dry deciduous forest of Rajasthan, Western India. The mean relative decomposition rate was maximum in the wet summer and minimum during dry summer. Rainfall and its associated variables exhibited greater control over litter decomposition than temperature. The concentrations of N and P increased in decomposing litter with increasing retrieval days. Mass loss was negatively correlated with N and P concentrations. The monthly weight loss was significantly correlated (P < 0.05) with soil moisture and rainfall in both wood and leaf litter. Tectona grandis was found to be most suitable tree species for plantation programmes in dry tropical regions as it has high litter deposition and decomposition rates and thus it has advantages in degraded soil restoration and sustainable land management.

Hybrid Control and Protection Scheme for Inverter Dominated Microgrids

  • Xu, Xiaotong;Wen, Huiqing;Jiang, Lin;Hu, Yihua
    • Journal of Power Electronics
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    • v.17 no.3
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    • pp.744-755
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    • 2017
  • With the high penetration of various sustainable energy sources, the control and protection of Microgrids has become a challenging problem considering the inherent current limitation feature of inverter-based Distributed Generators (DGs) and the bidirectional power flow in Microgrids. In this paper, a hybrid control and protection scheme is proposed, which combines the traditional inverse-time overcurrent protection with the biased differential protection for different feeders with different kinds of loads. It naturally accommodates various control strategies such as P-Q control and V-f control. The parameter settings of the protection scheme are analyzed and calculated through a fast Fourier transform algorithm, and the stability of the control strategy is discussed by building a small signal model in MATLAB. Different operation modes such as the grid-connected mode, the islanding mode, and the transitions between these two modes are ensured. A Microgrid model is established in PSCAD and the analysis results show that a Microgrid system can be effectively protected against different faults such as the single phase to ground and the three phase faults in both the grid-connected and islanded operation modes.