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1.
Point-to-point functional movements involve simultaneous shoulder and elbow joint rotations. In able-bodied subjects these movements are fully automatic, and feed-forward control ensures the synergistic activity of many muscles. Synergy between joint rotations was defined and described as a scaling between joint angular velocities [19]. Similarly, subjects who can control their shoulder movements may be assisted in reaching tasks by functional electrical stimulation (FES) of elbow extensor muscles. The synergistic control paradigm can be implemented in real-time by employing a hierarchically structured production-rules method. The use of production-rules necessitates the acquisition of knowledge and the assembly of a rule-base. A nonparametric technique was designed for the identification of the rules. The identification process was divided into two phases: determination of the scaling parameters, and determination of the stimulation parameters. The scaling parameters, needed for the coordination of movements, were determined in able-bodied subjects. Those depend exclusively on the initial and target positions of the hand. The number of scalings could be reduced by dividing the workspace into 12 zones. The stimulation parameters, needed for the execution of movements, were determined in subjects with paralyzed elbow extensor muscles by identifying triplets: elbow angular velocity, elbow angular acceleration (velocity increments), and the corresponding pulse durations for various classes of movements and loads attached to the hand. 相似文献
2.
Samarthya Bhagia Nidia C. Gallego Nitilaksha Hiremath David P. Harper Richard A. Lowden Richard R. Lowden Yunqiao Pu Uday Vaidya Soydan Ozcan Arthur J. Ragauskas 《应用聚合物科学杂志》2021,138(32):50797
High speed friction grinding has been used to grind plant and food substances in water but never been explored for grinding of thermoplastics like polylactic acid (PLA), low and high density polyethylene and polypropylene. Such grinding was investigated in this work and was made possible by using 0.5% guar gum solution instead of just water because increasing the viscosity of water reduced their settling and the speed of passing through the grinder. Tensile, flexural, and impact strengths of the plastics were studied and higher grinding efficiency of PLA could be explained by its low elongation-at-break compared to low density polyethylene, high density polyethylene, and polypropylene. The microplastics (2000–45 μm) were studied for mass and particle size distributions and by scanning electron microscopy, 13C CP/MAS NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. In addition, viscosity of guar gum and contact angles was measured. This new technology can produce finely ground microplastics (710–45 μm) for a variety of applications. 相似文献
3.
Summary Effects of free convection currents on the oscillatory flow of a polar fluid through a porous medium, which is bounded by a vertical plane surface of constant temperature, have been studied. The surface absorbs the fluid with a constant suction and the free stream velocity oscillates about a constant mean value. Analytical expressions for the velocity and the angular velocity fields have been obtained, using the regular perturbation technique. The effects of Grashof numberG; material parameters and ; Prandtl numberP; permeability parameterK and frequency parametern on the velocity and the angular velocity are discussed. The effects of cooling and heating of a polar fluid compared to a Newtonian fluid have also been discussed. The velocity of a polar fluid is found to decrease as compared to the Newtonian fluid.List of symbols
C
p
specific heat at constant pressure
-
g
acceleration due to gravity
-
G
Grashof number
-
K
+
permeability of the porous medium
-
K
dimensionless permeability
-
P
Prandtl number
-
t
+
time
-
t
dimensionless time
-
T
w
+
mean temperature of the surface
-
T
+
temperature of the fluid
-
T
+
temperature of the fluid away from the surface
-
density of the fluid
-
viscosity
-
r
rotational viscosity
-
C
a
,C
d
coefficients of couple stress viscosities
-
I
a scalar constant of dimension equal to that of the moment of inertia of unit mass
-
x
+,y
+
coordinate system
-
u
+,v
+
velocity components in thex
+ andy
+ directions
-
u
dimensionless velocity in thex
+-direction
- +
angular velocity component
-
dimensionless angular velocity
-
n
+
frequency of oscillations
-
n
dimensionless frequency
-
perturbation parameter
-
U
a constant velocity
-
u
0
mean velocity
-
u
1
fluctuating part of the velocity
- 0
mean angular velocity
- 1
fluctuating part of the angular velocity
-
T
0
mean temperature
-
T
1
fluctuating part of the temperature
- 0
coefficient of the volume expansion
-
kinematic viscosity
-
r
rotational kinematic viscosity
- ,
material parameters characterizing the polarity of the fluid
-
v
0
suction velocity
-
density of the fluid far from the surface
-
y
dimensionless coordinate normal to the surface 相似文献
4.
Journal of Mechanical Science and Technology - This study investigates the thermal property of fused quartz-reinforced aluminum 6061 alloy metal matrix composites for three different chill material... 相似文献
5.
V. Hiremath 《塑料、橡胶和复合材料》2016,45(5):199-206
Nanocomposites were synthesised by dispersing two different types of alumina nanoparticles in epoxy matrix by ultrasonication. Alumina nanoparticles of two shapes, rod and spherical were selected to investigate the effect of particle morphology on viscoelastic and flexural properties of nanocomposites. Specific surface area of both the selected nanoparticles was kept in the similar range. Good dispersion of nanoparticles was observed through transmission electron microscopy. The addition of nanoparticles in epoxy had significant enhancement in the viscoelastic properties and moderate improvement in flexural properties of composites. Composites having alumina nanorods showed higher improvement both in storage modulus as well as in flexural properties in comparison to composites having spherical alumina nanoparticles. Efficacy of Mori-Tanaka method was explored in modelling storage modulus of nanocomposites. Assorted size of alumina nanorods based on particle size distribution was used to model composites with nanorods to see the effect of size assortment on storage modulus. 相似文献
6.
7.
P. S. Hiremath 《Acta Mechanica》1983,46(1-4):271-279
8.
Basavaraj V. Hiremath Robert E. Newnham Leslie E. Cross 《Journal of the American Ceramic Society》1992,75(11):2953-2958
A new type of barrier layer capacitor is described utilizing thin glass layers on highly conducting ceramics of barium plumbate and barium bismuth plumbate. The frequency dispersion of the apparent dielectric constant has been explained using a modified version of the Maxwell–Wagner model. These capacitors have a low temperature coefficient of capacitance and a high dispersion frequency in the megahertz range. Simple processing conditions together with low firing temperature make it possible to produce the barrier layer capacitors inexpensively. 相似文献
9.
Microresonator filters, which are realized by evanescent coupling of circular cavities with two parallel bus waveguides, are promising candidates for applications in dense wavelength-division multiplexing. Tunability of these filters is an essential feature for their successful deployment. In this paper, we present a framework for modeling of tuning of the microresonators by changes in their cavity core refractive index. Using a reciprocity theorem, a perturbational expression for changes in the cavity propagation constants due to slight modifications of the cavity core refractive index is derived. This expression permits us to analytically calculate shifts in the spectral response of the 2-D resonators. Comparisons of the resultant shifts and spectra with direct simulations based on a coupled mode theory show satisfactory agreement. 相似文献
10.
The DOE's high-level waste storage tank (HLWST) sites consist of single- and double-shell concrete tanks covered with soil overburden. Due to the high temperature (212 °F and above) of the liquid-filled waste, the concrete walls and domed roofs are expected to endure thermal degradation which, in turn, may lead to cracking of the concrete. A remote video camera inspection of one such HLWST indicated some ‘irregularities’ on the inner surface of the tank dome. A finite element model using ADINA was developed to simulate the field conditions including concrete strength deterioration. The model was first validated against the results obtained from tests conducted on a 1/10th-scale model. The analysis was then extended to study the actual field behavior. The results confirmed the overall structural integrity of the tank by considering the global response of the tank and a detailed analysis of likely crack patterns in the dome area. The paper describes the complexities in validating the scale model as well as prototype response. 相似文献