38 research outputs found
ΠΡΠΎΠ΅ΠΊΡΠ½ΡΠΉ Π°Π½Π°Π»ΠΈΠ· Π°ΡΡΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΡ ΡΡ Π΅ΠΌ ΡΠΏΡΡΠΊΠ°Π΅ΠΌΡΡ Π°ΠΏΠΏΠ°ΡΠ°ΡΠΎΠ² ΠΊΠ°ΠΏΡΡΠ»ΡΠ½ΠΎΠΉ ΡΠΎΡΠΌΡ ΡΠΈΡΠ»Π΅Π½Π½ΡΠΌ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΠΏΠΎ Π½ΡΡΡΠΎΠ½ΠΈΠ°Π½ΡΠΊΠΎΠΉ ΡΠ΅ΠΎΡΠΈΠΈ ΠΎΠ±ΡΠ΅ΠΊΠ°Π½ΠΈΡ
The article objective is to review the basic design parameters of space capsule (SC) to select a rational shape at the early stages of design.The choice is based on the design parameters such as a volume filling factor (volumetric efficiency of shape), aerodynamic coefficients, margin of stability, and centering characteristics.The aerodynamic coefficients are calculated by a numerical method based on approximate Newton's theory. A proposed engineering technique uses this theory to calculate aerodynamic characteristics of the capsule shapes. The gist of the technique is in using a developed programme to generate capsule shapes and provide numerical calculation of aerodynamic characteristics. The accuracy of the calculation, performed according to proposed technique, tends to the results obtained by analytical integral dependencies according to the Newtonian technique.When considering the stability of the capsule shapes the paper gives a diagram of the aerodynamic forces acting on the SC in the descent phase, and using the aerodynamically-shaped SC "Soyuz" as an example analyses a dangerous moment of flow at adverse angles of attack.After determining a design center-of-mass position to meet the stability requirements it is necessary at the early stage, before starting the SC layout work, to evaluate the complexity of bringing the center-of-mass to the specified point. In this regard have been considered such design parameters of the shape as a volume-centering and surface-centering coefficients.Next, using the above engineering technique are calculated aerodynamic characteristics of capsule shapes similar to the well-known SC "Soyuz", "Zarya 2" and the command module "Apollo".All calculated design parameters are summarized in the table. Currently, among the works cited in foreign publications concerning the contours of winged configuration of the type "Space Shuttle" some papers are close to the proposed technique.Application of the proposed engineering technique allows a multi-fold increasing rate of the capsule shape analysis at an early designing stage. Reviewed design parameters can be further considered as the optimality criteria when choosing the SC shape, and the engineering technique can be further extended to a full-fledged programme on the numerical selection of the optimal aerodynamic solutions with continuously transferred results for engineering development of the SC.Π Π΄Π°Π½Π½ΠΎΠΉ ΡΡΠ°ΡΡΠ΅ ΡΠ°ΡΡΠΌΠΎΡΡΠ΅Π½Ρ ΡΡΠΈ ΡΠΈΠΏΠ° ΠΊΠΎΡΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠΏΡΡΠΊΠ°Π΅ΠΌΡΡ
Π°ΠΏΠΏΠ°ΡΠ°ΡΠΎΠ² (Π‘Π) ΠΊΠ°ΠΏΡΡΠ»ΡΠ½ΠΎΠΉ ΡΠΎΡΠΌΡ, Π°Π½Π°Π»ΠΎΠ³ΠΈΡΠ½ΡΡ
Π‘Π Β«Π‘ΠΎΡΠ·Β» ΠΈ Π‘Π Β«ΠΠΏΠΎΠ»Π»ΠΎΠ½Β». ΠΡΡΠ»Π΅Π΄ΡΡΡΡΡ Π°ΡΡΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΠ΅ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ ΡΡΠΈΡ
Π°ΠΏΠΏΠ°ΡΠ°ΡΠΎΠ² Π² Π³ΠΈΠΏΠ΅ΡΠ·Π²ΡΠΊΠΎΠ²ΠΎΠΌ Π΄ΠΈΠ°ΠΏΠ°Π·ΠΎΠ½Π΅ ΡΠΊΠΎΡΠΎΡΡΠ΅ΠΉ ΠΏΠΎ Π½ΡΡΡΠΎΠ½ΠΈΠ°Π½ΡΠΊΠΎΠΉ ΡΠ΅ΠΎΡΠΈΠΈ. ΠΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Π° ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ½Π°Ρ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠ° ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ Π°ΡΡΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊ ΠΊΠ°ΠΏΡΡΠ»ΡΠ½ΡΡ
Π°ΠΏΠΏΠ°ΡΠ°ΡΠΎΠ², ΠΊΠΎΡΠΎΡΠ°Ρ ΠΌΠΎΠΆΠ΅Ρ Π±ΡΡΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½Π° Π½Π° ΡΡΠ°Π΄ΠΈΠΈ ΠΏΡΠ΅Π΄Π²Π°ΡΠΈΡΠ΅Π»ΡΠ½ΡΡ
ΠΏΡΠΎΠ΅ΠΊΡΠ½ΡΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ. ΠΠ°Π½Π½Π°Ρ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠ° ΠΌΠΎΠΆΠ΅Ρ ΠΎΠΊΠ°Π·Π°ΡΡΡΡ Π²ΠΎΡΡΡΠ΅Π±ΠΎΠ²Π°Π½Π½ΠΎΠΉ Π² ΡΡΠ΅Π±Π½ΠΎΠΌ ΠΏΡΠΎΡΠ΅ΡΡΠ΅ Π΄Π»Ρ ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΡΡΡΠΈΡ
ΡΠΏΠ΅ΡΠΈΠ°Π»ΡΠ½ΠΎΡΡΠ΅ΠΉ. DOI: 10.7463/aersp.0415.081389
Thyroid cancer risk in Belarus among children and adolescents exposed to radioiodine after the Chornobyl accident
BACKGROUND: Previous studies showed an increased risk of thyroid cancer among children and adolescents exposed to radioactive iodines released after the Chornobyl (Chernobyl) accident, but the effects of screening, iodine deficiency, age at exposure and other factors on the dose-response are poorly understood.
METHODS: We screened 11β970 individuals in Belarus aged 18 years or younger at the time of the accident who had estimated (131)I thyroid doses based on individual thyroid activity measurements and dosimetric data from questionnaires. The excess odds ratio per gray (EOR/Gy) was modelled using linear and linear-exponential functions.
RESULTS: For thyroid doses \u3c5 \u3eGy, the dose-response was linear (n=85; EOR/Gy=2.15, 95% confidence interval: 0.81-5.47), but at higher doses the excess risk fell. The EOR/Gy was significantly increased among those with prior or screening-detected diffuse goiter, and larger for men than women, and for persons exposed before age 5 than those exposed between 5 and 18 years, although not statistically significant. A somewhat higher EOR/Gy was estimated for validated pre-screening cases.
CONCLUSION: 10-15 years after the Chornobyl accident, thyroid cancer risk was significantly increased among individuals exposed to fallout as children or adolescents, but the risk appeared to be lower than in other Chornobyl studies and studies of childhood external irradiation
The Flux-Line Lattice in Superconductors
Magnetic flux can penetrate a type-II superconductor in form of Abrikosov
vortices. These tend to arrange in a triangular flux-line lattice (FLL) which
is more or less perturbed by material inhomogeneities that pin the flux lines,
and in high- supercon- ductors (HTSC's) also by thermal fluctuations. Many
properties of the FLL are well described by the phenomenological
Ginzburg-Landau theory or by the electromagnetic London theory, which treats
the vortex core as a singularity. In Nb alloys and HTSC's the FLL is very soft
mainly because of the large magnetic penetration depth: The shear modulus of
the FLL is thus small and the tilt modulus is dispersive and becomes very small
for short distortion wavelength. This softness of the FLL is enhanced further
by the pronounced anisotropy and layered structure of HTSC's, which strongly
increases the penetration depth for currents along the c-axis of these uniaxial
crystals and may even cause a decoupling of two-dimensional vortex lattices in
the Cu-O layers. Thermal fluctuations and softening may melt the FLL and cause
thermally activated depinning of the flux lines or of the 2D pancake vortices
in the layers. Various phase transitions are predicted for the FLL in layered
HTSC's. The linear and nonlinear magnetic response of HTSC's gives rise to
interesting effects which strongly depend on the geometry of the experiment.Comment: Review paper for Rep.Prog.Phys., 124 narrow pages. The 30 figures do
not exist as postscript file
Project Analysis of Aerodynamics Configuration of Re-entry Π‘apsule-shaped Body Based on Numerical Methods for Newtonian Flow Theory
The article objective is to review the basic design parameters of space capsule (SC) to select a rational shape at the early stages of design.The choice is based on the design parameters such as a volume filling factor (volumetric efficiency of shape), aerodynamic coefficients, margin of stability, and centering characteristics.The aerodynamic coefficients are calculated by a numerical method based on approximate Newton's theory. A proposed engineering technique uses this theory to calculate aerodynamic characteristics of the capsule shapes. The gist of the technique is in using a developed programme to generate capsule shapes and provide numerical calculation of aerodynamic characteristics. The accuracy of the calculation, performed according to proposed technique, tends to the results obtained by analytical integral dependencies according to the Newtonian technique.When considering the stability of the capsule shapes the paper gives a diagram of the aerodynamic forces acting on the SC in the descent phase, and using the aerodynamically-shaped SC "Soyuz" as an example analyses a dangerous moment of flow at adverse angles of attack.After determining a design center-of-mass position to meet the stability requirements it is necessary at the early stage, before starting the SC layout work, to evaluate the complexity of bringing the center-of-mass to the specified point. In this regard have been considered such design parameters of the shape as a volume-centering and surface-centering coefficients.Next, using the above engineering technique are calculated aerodynamic characteristics of capsule shapes similar to the well-known SC "Soyuz", "Zarya 2" and the command module "Apollo".All calculated design parameters are summarized in the table. Currently, among the works cited in foreign publications concerning the contours of winged configuration of the type "Space Shuttle" some papers are close to the proposed technique.Application of the proposed engineering technique allows a multi-fold increasing rate of the capsule shape analysis at an early designing stage. Reviewed design parameters can be further considered as the optimality criteria when choosing the SC shape, and the engineering technique can be further extended to a full-fledged programme on the numerical selection of the optimal aerodynamic solutions with continuously transferred results for engineering development of the SC
Project Analysis of Aerodynamics Configuration of Re-entry Π‘apsule-shaped Body Based on Numerical Methods for Newtonian Flow Theory
The article objective is to review the basic design parameters of space capsule (SC) to select a rational shape at the early stages of design.The choice is based on the design parameters such as a volume filling factor (volumetric efficiency of shape), aerodynamic coefficients, margin of stability, and centering characteristics.The aerodynamic coefficients are calculated by a numerical method based on approximate Newton's theory. A proposed engineering technique uses this theory to calculate aerodynamic characteristics of the capsule shapes. The gist of the technique is in using a developed programme to generate capsule shapes and provide numerical calculation of aerodynamic characteristics. The accuracy of the calculation, performed according to proposed technique, tends to the results obtained by analytical integral dependencies according to the Newtonian technique.When considering the stability of the capsule shapes the paper gives a diagram of the aerodynamic forces acting on the SC in the descent phase, and using the aerodynamically-shaped SC "Soyuz" as an example analyses a dangerous moment of flow at adverse angles of attack.After determining a design center-of-mass position to meet the stability requirements it is necessary at the early stage, before starting the SC layout work, to evaluate the complexity of bringing the center-of-mass to the specified point. In this regard have been considered such design parameters of the shape as a volume-centering and surface-centering coefficients.Next, using the above engineering technique are calculated aerodynamic characteristics of capsule shapes similar to the well-known SC "Soyuz", "Zarya 2" and the command module "Apollo".All calculated design parameters are summarized in the table. Currently, among the works cited in foreign publications concerning the contours of winged configuration of the type "Space Shuttle" some papers are close to the proposed technique.Application of the proposed engineering technique allows a multi-fold increasing rate of the capsule shape analysis at an early designing stage. Reviewed design parameters can be further considered as the optimality criteria when choosing the SC shape, and the engineering technique can be further extended to a full-fledged programme on the numerical selection of the optimal aerodynamic solutions with continuously transferred results for engineering development of the SC.</p