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981.
Dong?Seop?LeeEmail author J.?Periaux L.?F.?Gonzalez K.?Srinivas E.?Onate 《Structural and Multidisciplinary Optimization》2012,45(3):433-450
There are many applications in aeronautical/aerospace engineering where some values of the design parameters/states cannot
be provided or determined accurately. These values can be related to the geometry (wingspan, length, angles) and or to operational
flight conditions that vary due to the presence of uncertainty parameters (Mach, angle of attack, air density and temperature,
etc.). These uncertainty design parameters cannot be ignored in engineering design and must be taken into the optimisation
task to produce more realistic and reliable solutions. In this paper, a robust/uncertainty design method with statistical
constraints is introduced to produce a set of reliable solutions which have high performance and low sensitivity. Robust design
concept coupled with Multi-Objective Evolutionary Algorithms (MOEAs) is defined by applying two statistical sampling formulas;
mean and variance/standard deviation associated with the optimisation fitness/objective functions. The methodology is based
on a canonical evolution strategy and incorporates the concepts of hierarchical topology, parallel computing and asynchronous
evaluation. It is implemented for two practical Unmanned Aerial System (UAS) design problems; the first case considers robust
multi-objective (single-disciplinary: aerodynamics) design optimisation and the second considers a robust multidisciplinary
(aero-structures) design optimisation. Numerical results show that the solutions obtained by the robust design method with
statistical constraints have a more reliable performance and sensitivity in both aerodynamics and structures when compared
to the baseline design. 相似文献
982.
Using genetic algorithm for the optimization of seismic behavior of steel planar frames with semi-rigid connections 总被引:1,自引:0,他引:1
Asghar?Vatani?OskoueiEmail author Sahand?Sarioletlagh?Fard Orhan?Aksogan 《Structural and Multidisciplinary Optimization》2012,45(2):287-302
Beam-column connections have a significant role in the results of the analysis and the design of steel frames. In this paper,
a genetic algorithm has been used for the non-linear analysis and design of steel frames. For minimizing the weight of frames,
while satisfying the applied constraints and restraints such as the limits of normal and combined stresses, criteria such
as target displacement(s) and the number and locations of plastic hinges were used. To analyze and design the frame elements,
I and box-shaped standard sections were used for beams and columns, respectively. Finally, some clues for finding optimizing
semi-rigid connection stiffness values for beam-to-column connections have been obtained. The degrees of these rigidities
are obtained by a genetic algorithm during the procedure of optimization in order to reach a frame with the minimum weight.
SAP2000 structural analysis program was used to perform modal analysis and linear and non-linear static solutions as well
as the design of the elements. A MATLAB program was written for the process of optimization. The procedure of optimization
was based on a weight minimization carried out for 9 steel frames. Thus, the optimum connection stiffness could be obtained
for minimizing the weight of the structure. The results show that the non-linear analysis gives less weight for short period
frames with semi-rigid connections compared to those of linear ones. However, by increasing the periods of frames, much less
weights are obtained in the case of non-linear analysis with semi-rigid connections. 相似文献
983.
Dina Had?iosmanovi? Damiano Bolzoni Pieter H. Hartel 《International Journal of Information Security》2012,11(4):231-251
SCADA (supervisory control and data acquisition) systems are used for controlling and monitoring industrial processes. We propose a methodology to systematically identify potential process-related threats in SCADA. Process-related threats take place when an attacker gains user access rights and performs actions, which look legitimate, but which are intended to disrupt the SCADA process. To detect such threats, we propose a semi-automated approach of log processing. We conduct experiments on a real-life water treatment facility. A preliminary case study suggests that our approach is effective in detecting anomalous events that might alter the regular process workflow. 相似文献
984.
James?Eves Vassili?V.?ToropovEmail author Harvey?M.?Thompson Nik?Kapur Jian?Fan Daniel?Copley Adrian?Mincher 《Structural and Multidisciplinary Optimization》2012,45(5):739-745
Supersonic jet pumps are simple devices with no moving parts, where a high velocity (primary) flow is used to pump a second
fluid. In this paper, Computational Fluid Dynamics (CFD) is combined with an optimization framework in order to develop a
tool for the rapid generation of jet pump designs. A key feature of the problem formulation is the transformation of the jet
pump design parameters in terms of geometric ratios. This approach dramatically reduces the number of unrealistic designs
covered by the Design of Experiments. Optimal Latin Hypercubes for surrogate model building and model validation points are
constructed using a permutation genetic algorithm and design points are evaluated using CFD. Surrogate models of primary and
entrained flow rates are built using a Moving Least Squares approach. A series of optimizations for various pump sizes are
performed using a genetic algorithm and Sequential Quadratic Programming, with responses calculated from the surrogates. This
approach results in a set of optimized designs, from which pumps for a wide range of flow rates can be interpolated. 相似文献
985.
Behrooz?HassaniEmail author Mostafa?Khanzadi S.?Mehdi?Tavakkoli 《Structural and Multidisciplinary Optimization》2012,45(2):223-233
The Isogeometric Analysis (IA) method is applied for structural topology optimization instead of finite elements. For this
purpose, a control point based Solid Isotropic Material with Penalization (SIMP) method is employed and the material density
is considered as a continuous function throughout the design domain and approximated by the Non-Uniform Rational B-Spline
(NURBS) basis functions. To prevent the formation of layouts with porous media, a penalization technique similar to the SIMP
method is used. For optimization an optimality criteria is derived and implemented. A few examples are presented to demonstrate
the performance of the method. It is shown that, dissimilar to the element based SIMP topology optimization, the resulted
layouts by this method are independent of the number of the discretizing control points and checkerboard free. 相似文献
986.
L M Iakushina Iu P Arkhapchev S I Ale?nik N V Blazheevich V A Isaeva I A Alekseeva E Iu Glinka N L Grishchenko L S Evert E I Prakhin 《Voprosy pitaniia》1992,(3):59-62
The effect of the prophylactic use of multivitamin "Undevitum" on parameters of vitamin providing of schoolchildren in Norilsk was studied. The results of the investigation showed a positive effect of the prophylactic vitamin administration on providing with vitamins of schoolchildren in Norilsk and proved the necessity of conducting mass vitamin administration to schoolchildren. 相似文献
987.
The authors discuss the results of ophthalmodynamometric tests used for the assessment of cerebro-retinal vessels reactivity following carbon dioxide baths and "peat collars". An analysis of systemic and local blood pressure in the ophthalmic artery measured with Weigelin and Lobstein technique enables to assess changes in blood pressures following a/m balneologic procedures. It was found that blood pressure does not change parallelly due to the mechanism of cerebral autoregulation. Transient decrease in blood pressure in the ophthalmic artery is produced by the dilatation of the internal carotid artery indicating a potent vasodilating action of carbon dioxide. 相似文献
988.
N. Klein U. D?hne U. Poppe N. Tellmann K. Urban S. Orbach S. Hensen G. Müller H. Piel 《Journal of Superconductivity》1992,5(2):195-201
We used a dielectric resonator technique for highly sensitive measurements of the temperature dependence of the microwave surface resistanceR
s
of 1×1 cm2 superconducting films at 18.7 GHz. It consists of a sapphire disc positioned on the film under investigation within a copper cavity which is acting as a radiation shield. In the TE01 oscillation mode the highly reproducible quality factor of about 105 results in a sensitivity of ±50 forR
s
measurements. The temperature dependence ofR
s
can be measured up to values as high as 1 . We have investigated several YBa2Cu3O7 thin films prepared by high oxygen pressure d.c. sputtering on LaAlO3 and NdGaO3. Our best films exhibit a pronounced nonlinear behavior of the d.c. resistivity(T) with(300K)/(100K) values of about 3.7. Those films show, besides the initial fall-off just belowT
c
, a further strong decrease ofR
s
at low temperatures. This was observed both at 18.7 GHz and 87 GHz, as measured by a conventional cavity end plate replacement technique. ForTTc/2 these films exhibit an exp (–T
c/T) dependence ofR
s
with-values around 0.4. These observations may be explained by a superconducting energy gap with 2/kT
c0.8 for charge carriers localized in the CuO chains for YBa2Cu3O7. 相似文献
989.
V V Khudole? 《Eksperimental?nai?a onkologii?a》1987,9(5):40-46
Aquarium fishes Danio rerio and Poecilia reticulata are recommended as test-objects for testing carcinogenic chemical agents. 30 compounds were tested for their action on these objects. The analysis of the incidence of induced tumors, period of their appearance and Iball index shows high sensitivity of the aquarium fishes to the carcinogenic action. Data are presented on the dynamics of experimental carcinogenesis, morphology of induced tumours, as well as on modifications of carcinogenesis (the role of environmental temperature, age, dose, exposition, etc.). Advantages and limitations of the "fish model" are compared with those found in the experiments carried on mammals. 相似文献
990.
Min?-Ho?LeeEmail author Dong?-Joo?Yoon Dae?-Hee?Won Tae?-Sung?Bae Fumio?Watari 《Metals and Materials International》2003,9(1):35-42
In the present study, commercial pure Ti and Ti-6Al-4V alloy specimens with and without alkali and heat treatments were implanted
in the abdominal connective tissue of mice. Conventional stainless steel 316L was also implanted for comparison. After three
months, their biocompatibility was evaluated byin vitro andin vivo experiments. Surface structural changes of specimens due to the alkali treatment and soaking in Hank’s solution were analyzed
by XRD, SEM, XPS and AES. An apatite layer, which accelerates the connection with bone, was formed more easily on the alkali
treated specimens than the non-treated specimens. The number of macrophages, which is known to increase as the inflammatory
reaction proceeds, was much lower for the alkali and heat treated specimens than for the others. The average thickness of
the fibrous capsule formed around the implant was much thinner for the alkali and heat treated specimens than for the others. 相似文献