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71.
A monolithic three-axis micro-g resolution silicon capacitive accelerometer system utilizing a combined surface and bulk micromachining technology is demonstrated. The accelerometer system consists of three individual single-axis accelerometers fabricated in a single substrate using a common fabrication process. All three devices have 475-/spl mu/m-thick silicon proof-mass, large area polysilicon sense/drive electrodes, and small sensing gap (<1.5 /spl mu/m) formed by a2004 sacrificial oxide layer. The fabricated accelerometer is 7/spl times/9 mm/sup 2/ in size, has 100 Hz bandwidth, >/spl sim/5 pF/g measured sensitivity and calculated sub-/spl mu/g//spl radic/Hz mechanical noise floor for all three axes. The total measured noise floor of the hybrid accelerometer assembled with a CMOS interface circuit is 1.60 /spl mu/g//spl radic/Hz (>1.5 kHz) and 1.08 /spl mu/g//spl radic/Hz (>600 Hz) for in-plane and out-of-plane devices, respectively. 相似文献
72.
SW Kang HZ Chae MS Seo K Kim IC Baines SG Rhee 《Canadian Metallurgical Quarterly》1998,273(11):6297-6302
Mammalian tissues express three immunologically distinct peroxiredoxin (Prx) proteins (Prx I, II, and III), which are the products of distinct genes. With the use of recombinant proteins Prx I, II, and III, all have now been shown to possess peroxidase activity and to rely on Trx as a source of reducing equivalents for the reduction of H2O2. Prx I and II are cytosolic proteins, whereas Prx III is localized in mitochondria. Transient overexpression of Prx I or II in cultured cells showed that they were able to eliminate the intracellular H2O2 generated in response to growth factors. Moreover, the activation of nuclear factor kappaB (NFkappaB) induced by extracellularly added H2O2 or tumor necrosis factor-alpha was blocked by overproduction of Prx II. These results suggest that, together with glutathione peroxidase and catalase, Prx enzymes likely play an important role in eliminating peroxides generated during metabolism. In addition, Prx I and II might participate in the signaling cascades of growth factors and tumor necrosis factor-alpha by regulating the intracellular concentration of H2O2. 相似文献
73.
A newly developed comparative molecular field analysis (CoMFA) technique, the cross-validated r2-guided region selection (CoMFA/q2-GRS) method, has been used to build a quantitative structure-activity relationship (3D-QSAR) for nonsteroidal estrogen receptor (ER) ligands. Ligands included in this study belong to a series of diethylstilbestrol (DES) and indenestrol analogues whose affinities for the mouse ER (mER) have been determined in our laboratory. The final model utilized 30 compounds and yielded a q2GRS (cross-validated r2, guided region selection) of 0.796, as compared to a q2 of 0.720 for conventional CoMFA, with a standard error of prediction of 0.594 at 3 principal components. This model was used to visualize steric and electrostatic features of the ligands that correspond with ER binding affinity. Results obtained from the CoMFA steric and electrostatic plots of this model have also been compared to information from the ER binding affinities of substituted estradiol analogues. This is in an effort to determine structural features of compounds in the CoMFA analysis that may correspond to those of the estradiol analogues and to further clarify the mode of binding of nonsteroidal ER ligands. 相似文献
74.
Effects of various baffle designs on acoustic characteristics in combustion chamber of liquid rocket engine 总被引:2,自引:0,他引:2
Chae?Hoon?SohnEmail author Seong-Ku?Kim Young-Mog?Kim 《Journal of Mechanical Science and Technology》2004,18(1):145-152
Effects of various baffle designs on acoustic characteristics in combustion chamber are numerically investigated by adopting
linear acoustic analysis. A hub-blade configuration with five blades is selected as a candidate baffle and five variants of
baffles with various specifications are designed depending on baffle height and hub position. As damping parameters, natural-frequency
shift and damping factor are considered and the damping capacity of various baffle designs is evaluated. Increase in baffle
height results in more damping capacity and the hub position affects appreciably the damping of the first radial resonant
mode. Depending on baffle height, two close resonant modes could be overlapped and thereby the damping factor for one resonant
mode is increased exceedingly. The present procedure based on acoustic analysis is expected to be a useful tool to predict
acoustic field in combustion chamber and to design the passive control devices such as baffle and acoustic resonator. 相似文献
75.
A method for the detection of ascorbic acid (AA) was developed using square wave anodic stripping voltammetric (SWASV) analysis with a glassy carbon electrode (GCE). The results indicated a sensitive oxidation peak current of AA on the GCE. A linear curve was obtained within a concentration range of 1-130.0 microg/L with a preconcentration time of 270 s. The relative standard deviation of 30.0 microg/L observed was 0.1016% (n = 12) under optimum conditions. The low detection limit (S/N) was pegged at 0.30 microg/L. Results showed that the method developed can be used to assay biological and pharmaceutical samples, and food samples, as well as other materials requiring AA analyses. 相似文献
76.
The two-dimensional suffix tree of an n × n square matrix A is a compacted trie that represents all square submatrices of
A[11]. For the off-line case, i.e., A is given in advance to the algorithm, it is known how to build it in optimal time, for
any type of alphabet size [11],[18]. Motivated by applications in Image Compression[22[, Giancarlo and Guaiana [14] considered
the on-line version of the two-dimensional suffix tree and presented an O(n2 log2 n)-time algorithm, which we refer to as GG. That algorithm is a nontrivial generalization of Ukkonen's on-line algorithm
for standard suffix trees [23]. The main contribution in this paper is an O(log n) factor improvement in the time complexity
of the GG algorithm, making it optimal for unbounded alphabets [9]. Moreover, the ideas presented here also lead to a major
simplification of the GG algorithm. Technically, we are able to preserve most of the structure of the original GG algorithm,
by reducing a computational bottleneck to a primitive operation, i.e., comparison of Lcharacters, which is here implemented
in constant time rather than O(log n) time as in GG. However, preserving that structure comes at a price. Indeed, in order
to make everything work, we need a careful reorganization of another fundamental algorithm: Weiner's algorithm for the construction
of standard suffix trees [24]. Specifically, here we provide a version of that algorithm which takes linear time and works
on-line and concurrently over a set of strings. 相似文献
77.
Nanda Gopal Sahoo Yong Chae Jung Jae Whan Cho 《Materials and Manufacturing Processes》2007,22(4):419-423
We report the electroactive shape memory composites obtained by shape memory polyurethane block copolymer (PU) and multi-walled carbon nanotubes (MWNTs), and polypyrrole (PPy). An addition of combined MWNTs and PPy contributed to an enhancement in conductivity of PU-MWNTs composites. PU containing 2.5% MWNTs showed better mechanical and thermal properties than other composites, but conductivity was not sufficient for showing the shape memory effect by applying electrical voltages. However, when the composite was lightly coated by PPy (2.5%), its conductivity was the highest than other composites. Such the conductivity of this composite was enough to show electroactive shape recovery by heating above transition temperature of 40-48°C due to melting of polycaprolactone soft segment domain. The good shape recovery of 90-96% could be obtained in the shape recovery test when an electric field of 25 V was applied. 相似文献
78.
Shifting the MIMO Paradigm 总被引:4,自引:0,他引:4
Gesbert D. Kountouris M. Heath R.W. Chan-Byoung Chae Salzer T. 《Signal Processing Magazine, IEEE》2007,24(5):36-46
Multi-user MIMO (MU-MIMO) networks reveal the unique opportunities arising from a joint optimization of antenna combining techniques with resource allocation protocols. Furthermore, it brings robustness with respect to multipath richness, allowing for compact antenna spacing at the BS and, crucially, yielding the diversity and multiplexing gains without the need for multiple antenna user terminals. To realize these gains, however, the BS should be informed with the user's channel coefficients, which may limit practical application to TDD or low-mobility settings. To circumvent this problem and reduce feedback load, combining MU-MIMO with opportunistic scheduling seems a promising direction. The success for this type of scheduler is strongly traffic and QoS-dependent, however. 相似文献
79.
Nadarajah N. Chang Joon Chae An Vu Tran Nirmalathas A. 《Photonics Technology Letters, IEEE》2007,19(20):1637-1639
A low-cost and bandwidth-efficient scheme for delivering video services to customers over a long reach, large split repeater-based optical access network is proposed and experimentally demonstrated. Video channels that are on radio-frequency subcarriers are electrically combined with regenerated downstream data at the repeater and delivered to the customers on a single wavelength channel. Experimental results show that error-free transmission can be obtained for all channels with adequate power budget to support a split ratio more than 64. 相似文献
80.