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排序方式: 共有191条查询结果,搜索用时 109 毫秒
1.
This study investigates the effects of cement type, curing temperature, and age on the relationships between dynamic and static elastic moduli or compressive strength. Based on the investigation, new relationship equations are proposed. The impact-echo method is used to measure the resonant frequency of specimens from which the dynamic elastic modulus is calculated. Types I and V cement concrete specimens with water-cement ratios of 0.40 and 0.50 are cured isothermally at 10, 23, and 50 °C and tested at 1, 3, 7, and 28 days.Cement type and age do not have a significant influence on the relationship between dynamic and static elastic moduli, but the ratio of static to dynamic elastic modulus approaches 1 as temperature increases. The initial chord elastic modulus, which is measured at low strain level, is similar to the dynamic elastic modulus. The relationship between dynamic elastic modulus and compressive strength has the same tendency as the relationship between dynamic and static elastic moduli for various cement types, temperatures, and ages. 相似文献
2.
Sul Gee Park Ho Cheol Jeong Jeong Won Kim Dong-Hwan Hwang Sang Jeong Lee 《International Journal of Control, Automation and Systems》2011,9(2):276-284
This paper proposes a magnetic compass fault detection method for GPS/INS/Magnetic compass integrated navigation systems.
The fault is assumed to be caused by the hard iron and soft iron effect and modeled as an abrupt change in the magnetic compass
output. In order to detect the fault, a test statistic related with only azimuth error measurement is determined. When a fault
is detected, the GPS/INS/Magnetic compass integrated navigation system is changed into a GPS/INS integrated navigation system
mode. In order to show the validity of the proposed method, computer simulation and van testing are carried out. The simulation
and van test results show that the proposed navigation system gives more accurate outputs than the GPS/INS/Magnetic compass
without the proposed method. 相似文献
3.
This paper provides generalized analysis of active filters used as electromagnetic interference (EMI) filters and active-power filters. Insertion loss and impedance increase of various types of active-filter topologies are described with applicable requirements and limitations as well as the rationale for selecting active-filter topology according to different applications. 相似文献
4.
Hyung-Min Ryu Ji-Woong Kim Seung-Ki Sul 《Industry Applications, IEEE Transactions on》2006,42(4):1062-1070
In this paper, a synchronous-frame current controller of a multiphase synchronous motor with open phases is proposed. The proposed method cannot only possess the superiority of a linear controller over the conventional hysteresis-type current controller but it also enables the current to be regulated without a steady-state error. The key idea is that all the harmonics of the current and voltage, which can still contribute to the torque positively, can be equivalently represented as dc components even under asymmetric fault conditions. Throughout this paper, a five-phase synchronous motor with one open phase is used as a practical example, and the basic concepts can be easily extended into an n-phase ac motor with multiple open phases, which has the arbitrary number or configuration of the remaining healthy phases. Experimental results prove the validity of the proposed modeling and control algorithm. 相似文献
5.
6.
James Eberwine Ditte Lovatt Peter Buckley Hannah Dueck Chantal Francis Tae Kyung Kim Jaehee Lee Miler Lee Kevin Miyashiro Jacqueline Morris Tiina Peritz Terri Schochet Jennifer Spaethling Jai-Yoon Sul Junhyong Kim 《Journal of the Royal Society Interface》2012,9(77):3165-3183
The building blocks of complex biological systems are single cells. Fundamental insights gained from single-cell analysis promise to provide the framework for understanding normal biological systems development as well as the limits on systems/cellular ability to respond to disease. The interplay of cells to create functional systems is not well understood. Until recently, the study of single cells has concentrated primarily on morphological and physiological characterization. With the application of new highly sensitive molecular and genomic technologies, the quantitative biochemistry of single cells is now accessible. 相似文献
7.
The functional capacities of the Heidenhain and Fanuc CNC systems are analyzed by comparing the control programs used in the machining of housing components [1–5]. 相似文献
8.
Human walking influences indoor air quality mainly by resuspending dust particles settled on the floor. This study characterized walking‐induced particle resuspension as a function of flooring type, relative humidity (RH), surface dust loading, and particle size using a consistent resuspension mechanism. Five types of flooring, including hardwood, vinyl, high‐density cut pile carpet, low‐density cut pile carpet, and high‐density loop carpet, were tested with two levels of RH (40% and 70%) and surface dust loading (2 and 8 g/m2), respectively. Resuspension fraction ra (fraction of surface dust resuspended per step) for house dust was found to be varied from 10?7 to 10?4 (particle size: 0.4–10 µm). Results showed that for particles at 0.4–3.0 µm, the difference in resuspension fraction between carpets and hard floorings was not significant. For particles at 3.0–10.0 µm, carpets exhibited higher resuspension fractions compared with hard floorings. Increased RH level enhanced resuspension on high‐density cut pile carpet, whereas the opposite effect was observed on hard floorings. Higher surface dust loading was associated with lower resuspension fractions on carpets, while on hard floorings the effect of surface dust loading varied with different RH levels. 相似文献
9.
Sung Jin Park Sul Ong Kim Sung Ouk Jung Mi-Hye Yi Yun-Hi Kim Soon-Ki Kwon 《Journal of Electronic Materials》2009,38(9):2000-2005
An organic field-effect transistor was fabricated based on a thin film of 1,4-bis-(2-naphthalen-2-ylvinyl)benzene (BNDV).
The organic semiconductor was deposited via thermal evaporation on a chemically modified silicon dioxide surface. The thermal,
optical, electronic, and surface properties of the BNDV compound were investigated by thermogravimetric analysis, differential
scanning calorimetry, ultraviolet–visible (UV–vis) absorption, photoluminescence spectroscopies, cyclic voltammetry, x-ray
diffraction, and atomic force microscopy. The BNDV had good oxidation stability and exhibited a field-effect performance with
a mobility of 0.062 cm2/V s, a subthreshold slope of 0.4 V, and an on/off ratio of 2.45 × 105. 相似文献
10.
Scientometrics - At the Leibniz Institute for Baltic Sea Research Warnemünde (the home institute of this paper), scientists have been exploring the common denominator between microplastics and... 相似文献