CC BY
19
1. The elements of wood-sinchevyh houses erected in seismic zones, the use of traditional connecting "Turm" type units (drills) — is not enough, because in terms of tensile and shear loads Sinchi elements may be destroyed.
2. Therefore it is recommended to install in knots metal mechanical connections such as clamp, bolt, screw, etc., That will strengthen resistance to opening the cells and the appearance of residual deformations in the plastic timber frame elements.
3. Currently, according to QMQ_2.03.08-98, the calculation of
timber frame elements (paragraph 4.16), are in conditions ofbend-ing and stretching is done taking into account the factor P = ,
R
which gives approximate values for any type ofwood. Offered in the coefficient ^ =-1-- allows to obtain more accurate re-
1 +
R
A t ■ 11
nt_0_
EI
suits, taking into account the rigidity of stretched-bent wood framing members.
References:
1. Slitskoukhov Yu. V. Konstruktsii iz dereva i plastmass [Tekst]: uchebnik dlya VUZov/Yu. V. Slitskoukhov, V. D. Budanov, M. M. Gap-poyev [i dr.];/pod red. G. G. Karlsena i Yu. V. Slitskoukhova. - 5-ye izd., pereab. i. dop. - M.: Stroyizdat, - 1986. - 543 p.: il.
2. QMQ2.03.08-98. Derevyanniye konstruktsii. Tashkent: Goskomarkhitektstroy R Uz. - 1998, - 46 p.
3. Razzakov S. J. Experimental and theoretical approach to the determination of physical and mechanical characteristics of the material of the walls of the low-strength materials [Text]/S. J. Razzakov//European Science Review-Austria, - 2016. - No. 7-8. - P. 215-216.
4. Razzakov S. J. The study of seismic stability of a single-storey building with an internal partition with and without taking into account the frame [Text]/S. J. Razzakov, S. A. Holmirzaev, B. G. Juraev//European Science Review-Austria, - 2016. - No. 7-8. - P. 217-220.
DOI: http://dx.doi.org/10.20534/ESR-17-1.2-225-227
Rahimov Shavkat Khudergenovich, Doctor of technical sciences, professor,
Begimov Ismoil
Research Institute of Irrigation and Water Problems of Tashkent Institute of Irrigation and Melioration Bakiev Masfarif Ruzmetovich, Doctor of technical sciences, professor, E-mail: [email protected] Shukurova Sevara Egamkulovna, assistant E-mail: [email protected] Kahharov Uktam Abdurakhimovich, Senior lecturer
of Tashkent Institute of Irrigation and Melioration E-mail: [email protected]
Modeling two-dimensional unsteady movement of flow, constrained by control structures
Abstract: The article describes the implementation of the model of two-dimensional unsteady movement of flow constrained by a combined dam on the basis of vector-matrix form of Saint-Venant equation in curvilinear coordinates.
Keywords: control structures, modeling, Saint-Venant equation, curvilinear coordinates, isoparametric transformations, boundary conditions, approximation, boundary and initial conditions, finite element method, algebraic equations, algorithm.
Introduction. Bank scouring annualy causes significant damage to the economy of Uzbekistan. Annually over 30 billion sums are allocated for bank protection and flood control works. Vast amount of funds are spent for reclamation work to eliminate emergency situations occurring as a result of existing dam breaks at Amudarya and Syrdarya rivers and their tributaries.
On the other hand the construction of large water reservoir hydrostructure systems at the main tributaries of the above rivers, Vahsh and Naryn, can result in lowering of water level for the existing non-dam water intake and respectively lower withdrawn discharge for large irrigation canals of the region.
Therefore protection and channel control works are being held at the heads of canals, dive culverts, aqueducts, at river port through
Termez and etc.
The main reasons for emergency situations and damages of protection and control structures (blank, through-flow and combined) are their imperfect structure and the methods of their calculation and design, associated with wrong prediction of channel reformation after their installation in river channel or floodplain.
In present, the justification of these protection structures is carried out mainly for steady-state conditions. Our proposed modeling method allows for justification of these structures on the basis of numerical experiments by the mathematical model [1] of two-dimensional unsteady movement of flow constrained by control structures.
Modeling. Inputting curvilinear coordinates x = x(£,,n), y = y(£,,n) and determining isoparametric transformation ele-
ments [2] into main Saint-Venant equation [1,2] and after simple algebraic transformations we get the following vector-matrix equation in curvilinear coordinates.
where
^ + a W V+ B*( V ^ + D^i V ) = 0
dt dâ, dn
V =
AW[V]=
(1)
0 4 + % 0
0
_ pq q% % + P %
h2 u %x u %x
P j 2 p q
_ +gh 2P % + q %
( h > (dh > (dh ) dn
p" dV dpi dV _ , dn dpi dn
I p'j dpn dpn I dn)
h
2q h
(3)
(2)
BSn[ V1 =
0
pq ' h2
2 p q —n +—n h '' h'y
-77 + gh 0 h
d^v]
gh
gh
3z„ 3z„
4 + nx —
" d§ x dn
§ — + n
y y dn
(nrp§ -§ypn){(np -§ypn) +(nj
+ gn
+ gn
2p p q
—n +—n +~n h lx h'y h'y
q p 2q p
~nx +~nx +—ny +~nx h h h h
, (4)
J 2h
{nxp* -Çxpn)((nyp§- §ypn )2 + (nxp*
/2
Boundary conditions in the system of curvilinear coordinates are written out:
the depth change or discharge change in the liquid part of the boundary is inputted
h = H , e da^ (6)
(-■qx cos a + ny sin a) + ( cos asin a )pn = JQ
" X ' (7)
A v '
a = (n, On), n) e dnM for the solid part of the boundary it is given as
(-■q cosa+n sma)p5+( cosa-^ sina)pn = 0,
A ^ ' ^ • (8)
a = (n, On), n) e dQTi i = 1,2 or in the operator form
E, V = F,, e da , i = 1,...,n (9)
Using implicit scheme of approximation in time, we obtain the following steady-state equation to determine:
dV k+1
= V1 - Df{ Vk It, dn 1 ; (10)
V*+' + Atn IV* It
dV *
- + Bini V* It
(x,y) eQ, k = 1,2,... Initial conditions,
V0 = V0, (x, y) eq, (11)
By discretizing the boundary conditions we obtain
EkVk+1 = Fk, (%,-q) e dQt , i = 1,...,n (12) Numerical solution algorithm. As the algorithm for numerical solution of the equation (10) we use the finite element method on the basis of Galerkin-Petrov scheme [3; 4; 5; 6; 7].
1. Triangular or rectangular elements are taken as finite elements for two-dimensional design field, and the rectangular element can be divided into two rectangular ones through diagonal. Dividing into elements must meet the requirements, and adjacent elements must have common sides and common enumerated nodes.
Domain of determination ofD variables is divided into N finite subdomains D. (i — 1, 2,.., N (for instance, irregular triangles and
N
rectangles, having areas of the same order), so that IjQj, npD =0,
i=1
for tej and then we move to isoparametric coordinates using bilinear
(5)
A73 ,
transformation;
2. Target function values, which are unknown values and are subject to be determined, are fixed in enumerated nodes.
3. Basis (q>. (I, n)} and (f. n)} are chosen — for subdomains
D;
4. Basis for elements are chosen from approximation criteria
5. Second basis (f. n)} is chosen as characteristic function of domain D.:
„ > J1, (in) , ( )
W; = 1 (13)
[0, (i;,n) ¿a.
6. Approximate solution Vjk+1 n) is searched in the following form:
V <k+1($,V) = i Q?^! ; (14)
where Qf+1 =
1,...,
J \
P,
n jk+1
1 ,...,n
1,...,nj
— vector-matrix of the unknown
coefficients and the amount of function in element approximations in the variable determination domain and q>. (1, n) — linear and quadratic basis functions in triangle and rectangle [3,8].
7. In order to determine coefficients Qjk+1 at all points of variable determination domain the following system of equations is used:
tu \
\k+1 + A H Vk It — + Bk Vk lt-dv "
dn
-Vk + Din( Vk T,
Ï (EkVk+1 - F,k, Vj), i<
: Ni
, j c Nsh (15) (16)
JJ[ Vt+1+A^(vk )t ———( Vk ïr^^— -Vk +D«"(Vk)T I 3a, =0, ,
" \ ^ ' dÇ V > dn ^ ' ) ' (17)
j c N
J 61
t j (Efn(■Vk )Vk+1 -Ffnk ) = 0, i c N (18)
where (u, v) — scalar product, . — number of boundaries in j-th element, n — number of nodes ofj-th element, included in domain
0
or
boundary, matrix elements E and F are determined with boundary conditions by of the equations (12) at the boundary dO.. Matrices A, B, E and vectors D, F for equations and boundary conditions [1] are used instead of matrices В?n, and vectors D^, if the equation is used with main coordinates.
8. Putting solutions into the equation and solving integrals, we obtain matrix system of algebraic equations for each element node and by linearizing by quasilinearization we obtain the following:
j - K (19)
Gjk Qjk+1 = Ujk+1 Rjk Qjk+1 = T.jk+1
j =
(20)
where G'kuU'k+1 matrices for coefficients obtained as a result of numerical integration.
9. By grouping and combining matrix elements G>k. and R^ U>k. and T/k. we obtain the system of linear algebraic equation with global matrices and vectors:
K4 Q4+1 = F*
(21)
where K h F>k+1 — global matrices and vectors with sizes equal to the amount of nodes.
10. Solving the system of equations on the basis of finite-difference method we obtain the function Q (t) for all nodes of the net. Then we move over to the main variables using inverse isoparametric transformation and obtain final solution, which determines the values for the initial function at any point of finite elements.
11. Then the clauses 6-9 are repeated for further steps in time.
The initial data is presented in the form of database on MICROSOFT ACCESS relational database, and the algorithm is carried out in the form of enquiries and program modules, developed in ACCESS BASIC language for Pentium computers using principles of structural programming.
Results and discussion. At the left side of rectangular channel discharge change liquid border is taken for boundary conditions and the boundary conditions at the right side is the change of water level 4.0m. The boundary conditions for blank part are taken for solid border. Carrying capacity and the type of build-up is taken into consideration for through-flow part [9; 10].
At the beginning of the numerical experiments the initial conditions are accepted, so that the velocity components are equal zero and the elevation of water is 4 m. The boundary conditions are as follows: water from the left border comes uniformly with along channel width with steady discharge of 0.8 m3/s, and at the end of channel it is supported by permanent 4.0 m. There is an occurrence of water flow parameter changes. Modeling of unsteady water motion at the given channel reach was carried out with time interval of 5 seconds during total of 2 hours.
Picture 1 — a, 6, b and r show velocity profiles at time moment of 120 seconds after the beginning of the process and for almost steady condition (the last picture) for case with combined spur dike, correspondingly.
Figure 1. Channel rectangular reach with combined straight spur dike
The scales for water flow velocities are at the left of the pictures. The pictures show the change of water flow velocity profiles in time along the channel length and width and the change of vortex zone beyond the dike, which changes in time along the channel length.
Conclusions
1. Usage of finite element method in water flow modeling gives the opportunity to model the operation of control structures for
unsteady flow regime, to determine the quantitative and qualitative flow characteristics along the length, width of river channel or river reach, and also allows to determine design parameters for control structures.
2. Upon modeling we can check operation regime of built control structures during the operation period in case of occurrence of unsteady flow motion.
References:
1. Рахимов Ш. Х., Бегимов И. Использовании метода конечных элементов для моделирования двумерного неустановившегося движения воды в открытых руслах.//Проблемы механики, - Ташкент. - Фан, - 2012. - № 3.
2. Кюнж Ж. А., Холли Ф. М., Вервей А. Численные методы в задачах речной гидравлики.
DOI: http://dx.doi.org/10.20534/ESR-17-1.2-228-230
Rakhmonov Hayriddin Kodirovich, Doctor of Technical Sciences, Professor Bukhara Engineering Technological, Institute Uzbekistan
E-mail: [email protected] Shodiyev Ziyadullo Ochilovich, Ph.D, Department"Technological and Equipment" Bukhara Engineering Technological, Institute, Uzbekistan
Oripov Zainiddin Bahodirovich, Department"Technological and Equipment" Bukhara Engineering Technological, Institute, Uzbekistan
Murodova Istat Nurillaevna, Department"Technological and Equipment" Bukhara Engineering Technological, Institute, Uzbekistan Zaripova Mohira Djuraevna, Department"Technological and Equipment" Bukhara Engineering Technological, Institute, Uzbekistan
Basis of saw updating of gin feeder in order to improve purifiering effect
Abstract: To create a new design of technological machines on the basis of a study of the dynamics of machine units, must be new technical solution taking into account the internal and external loads. This article provides mathematical models of cotton movementinside the drum of the feeder. Represented by the formula for determining the length of the drum pegs. Differential equations allows to obtain patterns of change in drum speed, taking into account the dissipative properties of the transmission, allows to define rational values of the dynamic parameters of drives.
Keywords: Gin, feeder drum, sheet, feed, screw, roller, soft impurities, material fabric tension, cotton.
The feeder is included in the overall Gin set installation and feeders are divided into feeders and purifying of feeders cleaners
provides equable feed of raw cotton in the working chamber of gin, raw cotton from small and large sort, in terms of volume of working
a thorough loosening and additional purifying it from trash before drums on the single drum and multi drum. the ginning process. By appointment in the process technological
a) b)
Figure1. Feeder raw cotton and cotton design scheme of movement on the surface of the drum chopping
