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1.
The humanoid robot SJTU-HR1’s concept is introduced and its characteristics tree is given. The basic states for SJTU-HR1 are
proposed, including lying, sitting, standing and handstanding, abstracted from the daily exercises of human beings. The G
F
(generalized function) set theory is exploited to achieve the kinematic characteristics of the interested EEs (end-effectors)
of SJTU-HR1 for the lying states. Finally, the results show that the large amounts of states can be described using the abbreviations
in a systematic manner. Although we have focused on the application of the G
F
set theory to humanoid robots, particularly the SJTU-HR1, this methodology can also be applied to quadruped robots and hexapedal
robots, especially when the desired tasks are complex.
Supported by the Natural Basic Research Program of China (“973”) (Grant No. 2006CB705400), the National Natural Science Foundation
of China (Grant Nos. 60534020, 30770538), Joint Research Fund for Young Scholars in China and Abroad (Grant No. 50728503),
and the Graduate Innovation Foundation of Shanghai Jiao Tong University 相似文献
2.
The stochastic averaging method for quasi-integrable Hamiltonian systems with time-delayed feedback bang-bang control is first
introduced. Then, two time delay compensation methods, namely the method of changing control force amplitude (CFA) and the
method of changing control delay time (CDT), are proposed. The conditions applicable to each compensation method are discussed.
Finally, an example is worked out in detail to illustrate the application and effectiveness of the proposed methods and the
two compensation methods in combination.
Supported by the National Natural Science Foundation of China (Grant No. 10772159), the Research Fund for the Doctoral Program
of Higher Education of China (Grant No. 20060335125), Zhejiang Natural Science Foundation (Grant No. Y7080070), and Fujian
Provincial Science and Technology Project (Grant No. 2005YZ1021) 相似文献
3.
This paper firstly evaluated the impedance method and traveling waves method for fault location, and studied the robustness
of fault location method based on impedance. Then it proposed an assembled fault location method for a transmission line based
on single-terminal electrical quantities, in which the fault zone was firstly determined by impedance method with robustness
then the accurate fault position was pinpointed by traveling waves method. EMTP (Electromagnetic Transient Program) simulations
showed that the proposed method can overcome the drawbacks of impedance method and traveling waves method when either one
is used alone, and improve both the accuracy and the reliability of fault location.
Supported by the National Natural Science Foundation of China (Grant Nos. 50077011 and 50377019) and the National Basic Research
Program of China (“973” Project) (Grant No. 2004CB217906) 相似文献
4.
The paper presents a practical dynamic security region (PDSR) based dynamic security risk assessment and optimization model
for power transmission system. The cost of comprehensive security control and the influence of uncertainties of power injections
are considered in the model of dynamic security risk assessment. The transient stability constraints and uncertainties of
power injections can be considered easily by PDSR in form of hyper-box. A method to define and classify contingency set is
presented, and a risk control optimization model is given which takes total dynamic insecurity risk as the objective function
for a dominant contingency set. An optimal solution of dynamic insecurity risk is obtained by optimizing preventive and emergency
control cost and contingency set decomposition. The effectiveness of this model has been proved by test results on the New
England 10-genarator 39-bus system.
Supported by the key research of the National Natural Science Foundation of China (Grant No. 50595413) and The National Basic
Research Program of China (973 Program) (Grant No. 2004CB217904) 相似文献
5.
The mechanical oscillatory behaviors of multiwall carbon nanotube oscillators in gaseous environment are investigated using
the molecular dynamics method. The effects of ambient gas and temperature on intertube frictional force and oscillation frequency
are analyzed. It is found that the intertube frictional force increases with the ambient gas density and temperature. Higher
gas density and higher temperature cause a more rapid decay in the oscillation amplitude and an increase of the oscillation
frequency. Compared to the vacuum environmental condition, the collision between gas atoms and the nanotube walls is a main
ingredient leading to the increase of the energy dissipation. Gas damping may be the main reason for the failure of carbon
nanotube oscillators working in gas environment. The ambient temperature also has an important effect on oscillations and
low temperature is advantageous to sustain oscillations.
Supported by the National Basic Research Program of China (“973”) (Grant No. 2006CB300404), the National Natural Science Foundation
of China (Grant Nos. 50676019, 50775017), the Jiangsu Province Natural Science Foundation (Grant Nos. BK2006510, BK2007113),
and the Research Funding for the Doctor Program from Chinese Educational Ministry (Grant No. 20050286019) 相似文献
6.
WenYao Xu 《中国科学E辑(英文版)》2008,51(10):1659-1664
Magnetic activity indices are widely used in theoretical studies of solar-terrestrial coupling and space weather prediction.
However, the indices suffer from various uncertainties, which limit their application and even mislead to incorrect conclusion.
In this paper we analyze three most popular indices, Kp, AE and Dst. Three categories of uncertainties in magnetic indices are discussed: “data uncertainty” originating from inadequate data
processing, “station uncertainty” caused by incomplete station covering, and “physical uncertainty” stemming from unclear
physical mechanism. A comparison between magnetic disturbances and related indices indicate that the residual Sq will cause an uncertainty of 1–2 in K measurement, the uncertainty in saturated AE is as much as 50%, and the uncertainty in Dst index caused by the partial ring currents is about a half of the partial ring current.
Supported by the National Natural Science Foundation of China (Grant No. 40436016), the National Basic Research Program of
China (“973”) (Grant No. 2006CB806305), and the KIP Pilot Project of the Chinese Academy of Sciences (Grant No. kzcx3-sw-144) 相似文献
7.
Pin-reinforced foam is a novel type of sandwich core materials formed by inserting pins (trusses) into a foam matrix to create
a truss-like network reinforced foam core. Upon loading, the pins deform predominantly by local stretching whilst the deformation
of foam is governed by local bending. This paper presents a theoretical study on the thermoelasticity of pin-reinforced foam
sandwich cores. To calculate the effective thermoelastic properties of pin-reinforced foam cores, the energy-based homogenization
approach is employed to develop a micromechanicsbased model, calibrated by the existing experimental data. It is found that
the stiffness of the sandwich core is mainly governed by pin reinforcements: the foam matrix contributes little to sandwich
stiffness. Compared with traditional foam cores without pin reinforcements, the changes in in-plane thermal expansion coefficients
are not vigorous as a result of pin reinforcements, while the throughthickness thermal expansion coefficient changes significantly.
It is also demonstrated that it is possible to design materials with zero or negative thermal expansion coefficients under
such a context.
Supported by the National Basic Research Program of China (Grant No. 2006CB601202), the National Natural Science Foundation
of China (Grant Nos. 10572111, 10632060), the National 111 Project of China (Grant No. B06024), the National High Technology
Research Development Program (Grant No. 2006AA03Z519), the NPU Foundation for Fundamental Research, the Open Foundation of
State Key Laboratory of Structural Analysis of Industrial Equipment (Grant No. GZ0701), and the NPU Foundation for Scientific
Innovation 相似文献
8.
JinBin Cao JunYing Yang ShiGan Yuan XuHui Shen YuanMo Liu ChunXiao Yan WenZhen Li Tao Chen 《中国科学E辑(英文版)》2009,52(7):2112-2118
Using the data from STAFF/TC-1, this paper for the first time analyzes the electromagnetic interferences of Chinese scientific
satellite. The electromagnetic interference of satellite exists mainly below 30 Hz, but can extend to 190 Hz with an obviously
decreasing power spectral density. The electromagnetic interferences at frequencies below 190 Hz have good correlation with
the solar aspect angle. The electromagnetic interferences at frequencies between 190 and 830 Hz have also correlation with
solar aspect angle. However, the electromagnetic interferences at frequencies above 830 Hz have no correlation with the solar
aspect angle. The correlation coefficient between solar aspect angel and electromagnetic interferences is around 0.90. The
larger the solar aspect angle, the stronger the satellite electromagnetic interference. When the solar aspect angle increases
from 90.6° to 93.6°, the electromagnetic interferences at frequencies <10 Hz increase by 8 times and those at frequencies
190–830 Hz increase by 60%. This close association of electromagnetic interferences with the solar aspect angle indicates
that the solar aspect angle is the main factor to determine the electromagnetic interferences. The electromagnetic interferences
of satellite in sunlight are larger than those in eclipse. The electromagnetic interference produced by solar panel occupies
about 87% in the low frequency band (<100 Hz) and 94% in the high frequency band (>100 Hz) of the total electromagnetic interference
produced by satellite. These in flight observations of electromagnetic radiation of satellites will be very helpful to the
designs of future satellites of space sciences or earthquake sciences.
Supported by the National Hi-Tech Research and Development Program of China (“863” Project) (Grant No. 2008AA12A216), the
National Science & Technology Supporting Program during the Eleventh Five-Year Plan, the National Natural Science Foundation
of China (Grant No. 40523006), the National Basic Research Program of China (“973” Project) (Grant No. 2006CB806305), and
the Specialized Research Fund for State Key Laboratories 相似文献
9.
The methods of homogenization and finite elements are employed to predict the effective elastic constants and stress-strain
responses of a new type of lattice structure, the X-structure proposed by the authors in a companion paper. It is shown that
in most cases the predictions by the equivalent homogenization theory agree well with the experimental and 3-dimensional finite
element calculated results. The theoretical and numerical study supports the argument that the X-structure is superior to
the pyramid lattice structure in terms of mechanical strength.
Supported by the National Basic Research Program of China (“973” Project) (Grant No. 2006CB601202), the National Natural Science
Foundation of China (Grant Nos. 10632060, 10825210), the National “111” Project of China (Grant No. B06024) and the National
High-Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA03Z519) 相似文献
10.
Open-celled metal foams fabricated through metal sintering offers novel mechanical, thermal and acoustic properties. Previously,
polymer foams were used as a means of absorbing acoustic energy. However, the structural applications of these foams are inherently
limited. The metal sintering approach provides a cost-effective means for the mass-production of open-cell foams from a range
of materials, including high-temperature steel alloys. The low Reynolds number fluid properties of sintered steel alloy (FeCrAlY)
foams were investigated in a previous study. The static flow resistance of the foams was modeled based on a cylinder and a
sphere arranged in a periodic lattice at general incidence to the flow, with the resulting predictions correlating well to
measurements. The application of the flow resistance in an acoustic model is the primary focus of the present study. The predictions
for the static flow resistance of the sintered foams are first used in a theoretical model to determine the characteristic
impedances, as well as the propagation constants of the foams. Subsequently, the predicted acoustic performance of the foams
is compared to experimental results. Finally, the design space for a simple acoustic absorber incorporating sintered foams
is examined, with the effects of absorber size, foam selection, and foam spacing explored.
Supported by the National Basic Research Program of China (Grant Nos. 2006CB601202, 2006CB601204), the National 111 Project
of China (Grant No. B06024), US Office of Naval Research (Grant No. N000140210117), the National Natural Science Foundation
of China (Grant Nos. 10572111, 10632060), and the National H-Tech Research and Development Program of China (Grant No. 2006AA03Z519) 相似文献
11.
The phonon spectrum of ordered zincblende Si50Ge50 alloy is calculated by ab initio method. The energy band structure at zero pressure and the pressure dependence of phonon dispersion curves are shown up to
20 GPa. The calculation finds a pressure-induced softening of the transverse acoustic phonon mode and the mode frequency reaching
zero at about 14 GPa, which indicate breaking of the symmetry and formation of a new phase under high pressure.
Supported by the National Natural Science Foundation of China (Grant No. 50771090), the State Key Program for Basic Research
of China (Grant No. 2005CB724404) and the Program for Changjiang Scholars and Innovative Team (Grant No. IRT0650) 相似文献
12.
Nonequilibrium molecular dynamics (MD) method was used to study the dielectrophoresis (DEP) motion of nanocolloids in non-uniform electric field. By changing the electric field strength and system temperature, aggregation phenomena of nanocolloids was analyzed. Simulation results showed that at normal temperature, though the Brownian force can affect the motion of colloids, the attractive force will increase quickly with the distance between colloids down to 12σ , which makes colloids aggregate. When the Brownian force is weak to colloid's motion, for the enhancement of electric field strength, the DEP force of colloid will increase and so did the attractive force, which finally quickens the aggregate speed. Simulation results also showed that the temperature' enhancement will increase the Brownian force of colloids, hence disturbing the colloids aggregation. Moreover, the DLVO theory was used to study the motion of a pair of interactional colloids, both the potential energy and the attractive force versus distance of colloids were presented, then the latter graph was used to compare with another graph elicited by MD method. Results showed that the two graphs were nearly the same, indicating the MD model accorded with the theory. 相似文献
13.
Open celled metal foams fabricated through the route of metal sintering are a new class of material that offers novel mechanical
and acoustic properties. The metal sintering approach offers a cost-effective means for the mass-production of open-cell foams
from a range of materials, including high-temperature steel alloys. The mechanical properties of open-celled steel alloy (FeCrAlY)
foams have been characterized in previous studies, with focus placed on the influence of processing defects on stiffness and
strength. In this work, the low-Reynolds number fluid properties of FeCrAlY foams were investigated both theoretically and
experimentally. Specifically, the static flow resistance of the sintered foams important for heat transfer, filtration and
sound absorption was modeled based on a cylinder and a sphere arranged in a periodic lattice at general incidence to the flow.
Experimental measurements were subsequently carried out to validate theoretical predictions, with good agreement achieved.
Supported by the National Basic Research Program of China (Grant Nos. 2006CB601202, 2006CB601204), the National 111 Project
of China (Grant No. B06024), US Office of Naval Research (Grant No. N000140210117), the National Natural Science Foundation
of China (Grant Nos. 10572111, 10632060), and the National Hi-Tech Research Development Program (Grant No. 2006AA03Z519) 相似文献
14.
ZiLi Xie Rong Zhang RuoLian Jiang Bin Liu HaiMei Gong XiangQian Xiu Peng Chen Hai Lu Ping Han Yi Shi YouDou Zheng 《中国科学E辑(英文版)》2009,52(2):332-335
AlN/Al0.3Ga0.7N superlattices were grown on (0001) sapphire substrate by metal-organic chemical vapor deposition (MOCVD). The superlattice
period varies from 6 to 30. The layer thickness of different period stack was designed. GaN or AlGaN template was employed
for growing AlN/AlGaN superlattices. Reflectivity, SEM, AFM and XRD data of the Al
x
Ga1-x
N/AlN superlattices are presented. It is found that the templates used have an intensive impact on surface roughness and interfacial
properties of following AlN/AlGaN superlattices. The result of atomic force microscopy indicates that AlN/AlGaN superlattices
grown on GaN template exhibit quasi-two-dimensional growth mode. The resulting superlattice has a smooth surface morphology
and distinct interface. No crack is observed in the area of a 2-inch wafer.
Supported by the Special Funds for Major State Basic Research Project (973 Project) (Grant No. 2006CB6049), the Hi-tech Research
Project (Grant Nos. 2006AA03A103, 2006AA03A118, and 2006AA03A142), the National Natural Science Foundation of China (Grant
No. 60676057), and the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050284004) 相似文献
15.
TieYing Zhou Yu Chen CunYue Lu DeYong Fu XiaoPing Hu Yi Li Bin Tian 《中国科学E辑(英文版)》2009,52(9):2591-2596
This paper introduces an integrated optical auto-focus system driven by a nut-type ultrasonic motor (USM). The system comprises
an optical lens as a rotor (M6 or M7), a polyhedral tube of copper as a stator; an image sensor, and a driver IC of the motor.
The sizes of the AF (auto-focus) module are 8.5 mm×8.5 mm×5.9 mm. The piezoelectric elements are bonded on the external surface
of the stator. The rotor has external screw thread that engages with the inner screw thread of the stator. When the piezoelectric
elements are excited by the driver IC, a bend traveling wave in plane is generated on the stator along the circle direction,
that drives the lens rotor to rotate and then to move axially. The driver IC is controlled by an image feedback of an image
sensor centered on the axis of the casing, then the optical focusing is realized. The power consumption is zero at rest and
is less than 0.25 W in motion; focusing precision <10 μm; speed >3 r/s(180 r/min); response <10 ms; high reliability: resistant
to shock and fall off; directly driven by the driver IC without transmission mechanism; the friction force is namely the driving
force and noiseless. The integrated optical auto-focus system is very useful, especially for cellular phones. The image resolution
of 3–5 MP has been obtained in the module prototypes of the cellular phone.
Supported by the National Natural Science Foundation of China (Grant Nos. 50577035, 10676015), High Technology Research and
Development Program of China (863 Program) (Grant No. 2006AA02Z472) 相似文献
16.
Reconstruction of a continuous time signal from its periodic nonuniform samples and multi-channel samples is fundamental for
multi-channel parallel A/D and MIMO systems. In this paper, with a filterbank interpretation of sampling schemes, the efficient
interpolation and reconstruction methods for periodic nonuniform sampling and multi-channel sampling in the fractional Fourier
domain are presented. Firstly, the interpolation and sampling identities in the fractional Fourier domain are derived by the
properties of the fractional Fourier transform. Then, the particularly efficient filterbank implementations for the periodic
nonuniform sampling and the multi-channel sampling in the fractional Fourier domain are introduced. At last, the relationship
between the multi-channel sampling and the filterbank in the fractional Fourier domain is investigated, which shows that any
perfect reconstruction filterbank can lead to new sampling and reconstruction strategies.
Supported by the National Natural Science Foundation of China for Distinguished Young Scholars (Grant No. 60625104), the National
Natural Science Foundation of China (Grant Nos. 60890072, 60572094) and the National Key Basic Research Program Founded by
MOST (Grant No. 2009CB724003) 相似文献
17.
With the rapid development of functional magnetic resonance imaging (fMRI) technology, the spatial resolution of fMRI data
is continuously growing. This provides us the possibility to detect the fine-scale patterns of brain activities. The established
univariate and multivariate methods to analyze fMRI data mostly focus on detecting the activation blobs without considering
the distributed fine-scale patterns within the blobs. To improve the sensitivity of the activation detection, in this paper,
multivariate statistical method and univariate statistical method are combined to discover the fine-grained activity patterns.
For one voxel in the brain, a local homogenous region is constructed. Then, time courses from the local homogenous region
are integrated with multivariate statistical method. Univariate statistical method is finally used to construct the interests
of statistic for that voxel. The approach has explicitly taken into account the structures of both activity patterns and existing
noise of local brain regions. Therefore, it could highlight the fine-scale activity patterns of the local regions. Experiments
with simulated and real fMRI data demonstrate that the proposed method dramatically increases the sensitivity of detection
of fine-scale brain activity patterns which contain the subtle information about experimental conditions.
Supported by Chair Professors of Changjiang Scholars Program and CAS Hundred Talents Program, National Program on Key Basic
Research Projects (Grant No. 2006CB705700), National High-Tech R&D Program of China (Grant No.2006AA04Z216), National Key
Technology R&D Program (Grant No. 2006BAH02A25), Joint Research Fund for Overseas Chinese Young Scholars (Grant No.30528027),
National Natural Science Foundation of China (Grant Nos.30600151, 30500131 and 60532050), and Natural Science Foundation of
Beijing (Grant Nos. 4051002 and 4071003) 相似文献
18.
The development of Hydro-Informatic Modelling System (HIMS) provides an integrated platform for hydrological simulation. To
extend the application of HIMS, an ecohydrological modeling system named ecohydrological assessment tool (EcoHAT) has been
developed. Integrating parameter-management tools, RS (remote sensing) inversion tools, module-design tools and GIS analysis
tools, the EcoHAT provides an integrated tool to simulate ecohydrological processes on regional scale, which develops a new
method on sustainable use of water. EcoHAT has been applied to several case studies, such as, the Yellow River Basin, the
acid deposition area in Guizhou province and the riparian catchment of Guanting reservoir in Beijing. Results prove that EcoHAT
can efficiently simulate and analysis the ecohydrological processes on regional scale and provide technical support to integrated
water resources management on basin scale.
Supported by the National Key Technology R&D Program in the 11th Five-year Plan of China (Grant No. 2006BAB06B07), the National
Natural Science Foundation of China (Grant No. 40671123), the National Basic Research Program of China (“973” Project) (Grant
Nos. 2005CB422207, G19990436), and the National Hi-Tech Research and Development Program of China (“863” Project) (Grant No.
2006AA12Z145) 相似文献
19.
A new transient stability margin is proposed based on a new expression of dynamic security region (DSR) which is developed
from the existing expression of DSR. Applications of the DSR based transient stability margin to contingency ranking and screening
are discussed. Simulations in the 10-machine 39-bus New England system are performed to show the effectiveness of the proposed
DSR based transient stability margin.
Supported by Chinese National Basic Research Program (Grant No. 2004CB217900), the National Natural Science Foundation of
China (Grant Nos. 50525721, 50595411, 50707035) and China Postdoctoral Science Foundation (Grant No. 20060400518) 相似文献
20.
QingZhao Zhang ChangQing Xie Ming Liu Bing Li BaoQin Chen XiaoLi Zhu 《中国科学E辑(英文版)》2008,51(11):1990-1994
The punching thru mechanism of gate oxide (thickness about 15A) was investigated. Because of the thin thickness of gate oxide,
gate oxide punching thru may easily happen during the plasma process. It was found that what caused the punching thru was
not only the selectivity of poly-silicon/oxide but also the pattern topography. We used the basic SRAM pattern to check this
topography effect, and found that gate oxide located at the narrow spacing of two parallel serpentine lines was the most easily
punched thru. What caused the topography effect was the starvation of oxygen in these places which were induced by the residue
of poly-silicon and enhanced by electron shading effect. So, to solve the issue of gate oxide punching thru, firstly the selectivity
should be enough, secondly we should pay attention to the etching pattern topography.
Supported by the National High-Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA843134) and
the National Basic Research Program of China ("973" Project) (Grant No. 2007CB935302) 相似文献