Heat-transfer processes for a supersonic
spatial flow around a spherically
blunted cone were studied by solving
direct and inverse three-dimensional
problems taking into account heat flow
along the longitudinal and
circumferential coordinates. It is shown
that highly heat-conducting materials
can be used to advantage to decrease the
maximum temperatures on the windward
side of streamline bodies. P. 120-127
A linearized system of equations
governing elastic deformation of a thin
plate with arbitrary boundary conditions
at its faces in an arbitrary curvilinear
coordinate system is proposed. This
system of equations is the first
approximation of a one-parameter
sequence of equations of two-dimensional
problems obtained from the initial
three-dimensional problem by
approximating unknown functions by
truncated series in Legendre
polynomials. The stability problem of an
infinite plate compressed uniaxially is
solved. The results obtained are
compared with the existing solutions.
P. 133-139
The paper considers a thick-walled long
conical tube from an ideal plastic
material whose inner surface is suddenly
subjected to time-constant, uniformly
distributed pressure or is given a
velocity. An ideal-plastic zone
propagates from the inner conical
surface. It is assumed that the material
of the tube is incompressible in both
the elastic and plastic zones. The
plastic material obeys the
Houber<!ndash!>Mises plasticity
condition. P. 140-146
An asymptotic solution of the contact
problem of an elastic body indented
(without friction) by a circular punch
with a flat base is obtained under the
assumption of a small relative size of
the contact zone. The resulting formulas
involve integral characteristics of the
elastic body, which depend on its shape,
dimensions, fixing conditions, Poisson's
ratio, and location of the punch center.
These quantities have the mechanical
meaning of the coefficients of local
compliance of the elastic body.
Relations that, generally, reduce the
number of independent coefficients in
the asymptotic expansion are obtained on
the basis of the reciprocal theorem.
Some coefficients of local compliance at
the center of an elastic hemisphere are
calculated numerically. The asymptotic
model of an elastic body loaded by a
point force is discussed.
P.147-153
V. N. Rusak, A. G. Fedorenko, M. A. Syrunin, L. A. Sobol'*, A. V. Sukhanov*, V. G. Popov*
Institute of Experimental Physics, Sarov 607190 *Institute of Mechanical Engineering, Moscow Region, Khot'kovo 141350
The dynamic behavior of thin-wall
members manufactured from materials with
the pyroelectric effect was studied. A
variational formulation of the problem
is used, and a variational principle is
formulated that differs from the well-
known one. Correct boundary-value
problems describing the tension,
compression, and bending of a thin-wall
pyroelectric member are constructed
using the variational principle and a
number of hypotheses on the distribution
of the components of physical fields
along the width of the member. P. 162-
167
L. B. Zuev, B. S. Semukhin, A. G. Lunev
Institute of Strength Physics and Material Science, Siberian Division, Russian Academy of Sciences, Tomsk 634021
The dependence of the propagation
velocity of ultrasonic waves on the
acting stress in plastically deformable
polycrystalline metals and alloys is
examined. The relationship between the
acting stress and the velocity of
ultrasound is found to be linear; this
dependence is typical of all materials
studied. A method is proposed for
determining the time resistance to
breakdown of materials (ultimate
strength)for the case of deformation in
the region of small plastic strains
without failure of the specimens.
P. 168-170
The paper gives an exact formula for
determining the intensity of an optical
field at the center of a spherical
particle of arbitrary radius obtained by
evaluating an indeterminate form of the
0/0 type of Mie theory for the electric-
field components at the center of the
sphere. This formula is valid for
arbitrary values of the complex
refractive index of the particle
material and arbitrary wavelengths of
the incident radiation. An approximation
for large particles and two
approximations for particle sizes less
than 10-4 cm are obtained.
The solution obtained for the optical-
field intensity at the center of small
particles coincides with the classical
Lorentz formula for local fields. P.
171-173
In connection with the development of an ecological crisis and with the awareness of its consequences, the concept of "sustainable development" has been put forward. However, no project or plan of such development has been proposed so far. In the present work, an approach to creation of a scientific concept of sustainable development is proposed. The approach is based on the "closed state" principle. In accordance with this principle, any system with the chemical transformations going in it can exist during an infinite time only if a complete substance cycle exists within it due to free energy supplied to it from outside. The problem of possibility of attaining a global closed state of the biosphere together with the technosphere remains disputable; however, the higher the closeness of the system is, the longer existence of the civilization may be planned. In order to approach the global closed state, it is necessary to develop adequate criteria of optimality and estimation of newly created technologies and reconstruction of the old ones, to be able to analyze the openness of at least the main mass flows in the bio-and technosphere, to develop working models. The developed models have to be checked with the help of artificial experimental biosphere.
