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排序方式: 共有1774条查询结果,搜索用时 78 毫秒
51.
Thermal Isolation of Encapsulated MEMS Resonators 总被引:1,自引:0,他引:1
Jha C.M. Hopcroft M.A. Chandorkar S.A. Salvia J.C. Agarwal M. Candler R.N. Melamud R. Bongsang Kim Kenny T.W. 《Journal of microelectromechanical systems》2008,17(1):175-184
This paper presents an in-chip thermal-isolation technique for a micro-ovenized microelectromechanical-system resonator. Resonators with a microoven can be used for high-precision feedback control of temperature to compensate for the temperature dependence of resonator frequency over a wide temperature range. However, ovenization requires power consumption for heating, and the thermal time constant must be minimized for effective temperature control. This paper demonstrates an efficient local-thermal-isolation mechanism, which can reduce the power requirement to a few milliwatts and the thermal time constant to a few milliseconds. In this method, the mechanical suspension of the resonator is modified to provide thermal isolation and include an integrated resistive heater. This combination provides mechanical suspension, electrical heating, and thermal isolation in a compact structure that requires low heating power and has a small thermal time constant. A power consumption of approximately 12 mW for a 125degC temperature rise and a thermal time constant ranging from 7 to 10 ms is reported in this paper, which is orders of magnitude lower than that of commercially available ovenized quartz resonators. A CMOS-compatible wafer-scale encapsulation process is used to fabricate this device, and the thermal-isolation design is achieved without any modification to the existing resonator fabrication process. 相似文献
52.
To overcome the problem of distance in global software development, various managers are experimenting and quickly adjusting their tactical approaches. We discuss some emerging approaches and explain their motivations from conceptual and practical perspectives. The most intuitive approach for alleviating distance is to apply communication technologies, but this is not our focus. Rather, we examine tactics that go beyond communication technologies, tactics aimed at reducing intensive collaboration, national and organizational cultural differences, and temporal distance 相似文献
53.
Recovering 3D human pose from monocular images 总被引:8,自引:0,他引:8
54.
With the rapid growth of the availability and popularity of interpersonal and behavior-rich resources such as blogs and other social media avenues, emerging opportunities and challenges arise as people now can, and do, actively use computational intelligence to seek out and understand the opinions of others. The study of collective behavior of individuals has implications to business intelligence, predictive analytics, customer relationship management, and examining online collective action as manifested by various flash mobs, the Arab Spring (2011) and other such events. In this article, we introduce a nature-inspired theory to model collective behavior from the observed data on blogs using swarm intelligence, where the goal is to accurately model and predict the future behavior of a large population after observing their interactions during a training phase. Specifically, an ant colony optimization model is trained with behavioral trend from the blog data and is tested over real-world blogs. Promising results were obtained in trend prediction using ant colony based pheromone classier and CHI statistical measure. We provide empirical guidelines for selecting suitable parameters for the model, conclude with interesting observations, and envision future research directions. 相似文献
55.
56.
A three-axis SOI accelerometer sensing with both in-plane and vertical comb electrodes 总被引:1,自引:0,他引:1
A three-axis capacitive accelerometer based on silicon-on-insulator is designed and fabricated. In the accelerometer, totally
eight groups of capacitors are compactly arranged around an octagonal proof mass. The four groups of capacitors along orthogonal
direction with in-plane comb electrodes detect XY acceleration, while the other four groups of capacitors along diagonal direction with vertical comb electrodes detect Z acceleration.
Measurements of in-plane and vertical motion by the respective in-plane and vertical comb electrodes enable direct detection
for all the three axes with differential capacitive sensing scheme. For the fabricated accelerometer in the size of 4 × 4 mm2, the capacitance sensitivities of in-plane and out-of-plane accelerometers are 145.3 and 9.1 fF/g, respectively. 相似文献
57.
D. C. Agarwal S. Sarin K. Wadhwa R. Vishwakarma M. B. Deshmukh S. Kurian 《Journal of Failure Analysis and Prevention》2005,5(6):70-78
The work presented in Part 1 of this article showed that additions of magnesium chloride (MgCl2) to ammonia solutions reduced the tendency of ammonia-induced stress-corrosion cracking (SCC) initiation in a Cu-5%Ni alloy.
The present work was undertaken to study the SCC behavior of the test alloy exposed to ammonia in the presence of varying
concentrations of MgCl2. The exposure to MgCl2 additions reduced the severity of the ammonia-induced SCC. 相似文献
58.
R. P. Agarwal D. O'Regan I. Rach
nkov S. Stan
k 《Computers & Mathematics with Applications》2003,46(12):1799-1826
The existence of solutions for singular higher-order differential equations with the Lidstone or the (n,p) boundary conditions is proved. The right-hand sides of differential equations can have singularities in the zero value of their phase variables and so higher derivatives of solutions changing their signs can pass through these singularities. Proofs are based on the method of a priori estimates, the degree theory arguments and on Vitali's convergence theorem. 相似文献
59.
J. Menghani S. K. Agrawal Vikram Agarwal Dhaval Bhatt 《Transactions of the Indian Institute of Metals》2012,65(1):107-109
Reduced weight of automobiles for the purpose of fuel economy has encouraged the use of light metals especially aluminium
alloys. A356 Al alloy containing 7% Si and 0.3% Mg is widely used in automobile and aircraft industries due to excellent castability,
good corrosion resistance and good pressure tightness. A356 is age hardenable alloy and there is appreciable improvement in
strength and hardness achievable due to precipitation of intermetallic compound Mg2Si. In the present investigation, aluminium alloy A356 with and without rare earth (RE) addition (0.5 wt%) was subjected to
single ageing as well as double aging treatment. The results were compared for mechanical properties like hardness and ultimate
tensile strength with the material not containing RE additions. 相似文献
60.
Ram Avtar Jat Ripandeep Singh S.C. Parida A. Das Renu Agarwal K.L. Ramakumar 《International Journal of Hydrogen Energy》2014
In the present study, we have for the first time reported the occupancy of deuterium in a new interstitial site of ZrCoD3 which explain the hydrogen induced disproportionation behavior of ZrCo alloy. We have also reported the effect of Ni substitution on interstitial site occupancy of deuterium in ZrCo1−xNixD3, which in turn explains the improved durability of these Ni substituted deuterides against disproportionation. The crystal structure of the ZrCo1−xNix (x = 0.0, 0.1, 0.2, 0.3) deuterides was investigated by X-ray powder diffraction and neutron diffraction methods. The XRD data reveals a single phase formation for all deuterides with varying Ni content (x). The neutron diffraction study shows that deuterium occupies a new site 8e in addition to 4c2 and 8f1. Additionally, the Zr–D distance in 8e site is shorter than that in ZrD2. Therefore, increase in 8e site occupancy will in turn decreases the durability against disproportionation and vice-versa. Furthermore, the neutron diffraction reveals that occupancy of new 8e site decreases and its Zr–D distance increases with increase in Ni content, which explicate the higher durability against disproportionation for Ni rich compound. 相似文献