Optimal control of the dynamic stability for robotic vehicles in rough terrain

In this paper, we mount semi-active suspensions between the wheels and platform of a robotic vehicle to absorb the vibrations caused by movement over rough terrain. The semi-active suspension consists of a spring and a magneto-rheological damper. By combining the dynamic model of the suspended robotic vehicle and the control model of the damper, we propose a new methodology to evaluate the dynamic stability of the vehicle. The model considers the configuration of semi-active suspensions and the road-holding ability of robotic vehicles. Based on the stability criterion, we use the particle swarm optimization method to search the optimum semi-active damping characteristics. The control model of the semi-active damper is checked by sinusoidal response analysis. To verify the dynamic stability criterion and the control method, we evaluate the proposed methodology by simulating a rough pavement condition and comparing the effectiveness of the method to a passive suspension. The results show that the proposed stability criterion is feasible, and the optimal control method yields a substantially improved dynamic stability when the vehicle moves through rough terrain.     

Dynamical analysis of the induced fission time obtained by the crystal blocking technique for the 235U + α reaction

The crystal blocking technique has been used to measure the total time of the induced fission process for the ²³⁵U + α reaction in the energy rage of bombarding α-particles from 25.9 to 31.2 MeV. The experimental fission lifetimes observed in this reaction vary from 10⁻¹⁷ to 10⁻¹⁶ s, depending on the projectile energy. The experimental data (along with the corresponding data on the angular anisotropy and fissionability of Pu isotopes produced in the investigated reaction) have been analyzed within the dynamic-statistical approach with allowance for the nuclear dissipation phenomenon and the double-humped fission barrier model. It is demonstrated that the time of induced fission reaction at low excitation energies is sensitive to the nuclear viscosity. Original Russian Text ? A.A. Dermenev, V.A. Drozdov, D.O. Eremenko, F. Malaguti, P. Olivo, S.Yu. Platonov, V. Togo, A. Uguzzoni, O.V. Fotina, O.A. Yuminov, 2009, published in Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya, 2009, Vol. 73, No. 6, pp. 882–886.     

Results of the search for strange quark matter and Q-balls with the SLIM experiment

The SLIM experiment at the Chacaltaya high altitude laboratory was sensitive to nuclearites and Q-balls which could be present in the cosmic radiation as possible Dark Matter components. It was sensitive also to strangelets, i.e. small lumps of Strange Quark Matter predicted at such altitudes by various phenomenological models. The analysis of 427 m² of Nuclear Track Detectors exposed for 4.22 years showed no candidate event. New upper limits on the flux of downgoing nuclearites and Q-balls at the 90% C.L. were established. The null result also restricts models for strangelets propagation through the Earth atmosphere.     

Octonionic Yang–Mills instanton on quaternionic line bundle of Spin(7) holonomy

The total space of the spinor bundle on the four-dimensional sphere S⁴ is a quaternionic line bundle that admits a metric of Spin(7) holonomy. We consider octonionic Yang–Mills instanton on this eight-dimensional gravitational instanton. This is a higher dimensional generalization of (anti-) self-dual instanton on the Eguchi-Hanson space. We propose an ansatz for Spin(7) Yang–Mills field and derive a system of non-linear ordinary differential equations. The solutions are classified according to the asymptotic behavior at infinity. We give a complete solution when the gauge group is reduced to a product of SU(2) subalgebras in Spin(7). The existence of more general Spin(7) valued solutions can be seen by making an asymptotic expansion.     

Studies on the formation of alkyl radicals from alkyl aryl tellurides and their application to the synthesis of carbocyclic C-nucleoside analogs

The photochemically initiated reactions and the atmospherically initiated reactions of alkyl aryl tellurides with electron-deficient heteroaromatic bases in the presence of N-acetoxy-2-thiopyridone and triethylborane, respectively, have been investigated. These reactions were applied to the preparation of carbocyclic four-membered C-nucleoside analogs. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8: 411–419, 1997     

Photochemical reduction of n-tosylsulfilimines with thiolate anion

The reaction between N-tosyldiarylsulfilimines and p-toluenethiolate anion did not take place in the dark even upon heating up to 62° but proceeded smoothly upon irradiation with visible light in DMF at room temperature, affording S-N bond cleavage products.     

Synthesis, stereochemistry, and reactions of 2,5-diphenylsilacyclopentenes

1,1-Disubstituted derivatives of 2,5-diphenylsilacyclopent-3-enes, namely those having the 1,1-diphenyl, 1,1-dimethyl, 1-alkoxy-1-methyl and 1,1-dialkoxy, were prepared by a one-pot reaction of (1E, 3E)-1,4-diphenyl-1,3-butadiene and dichlorosilanes in the presence of magnesium. Each silacyclopentene was formed as a mixture of one trans and two cis isomers. 1-Ethoxy-1-methyl-2,5-diphenylsilacyclopent-3-ene and 1,1-diethoxy-2,5-diphenylsilacyclopent-3-ene were reacted with optically active alcohols to furnish the corresponding diastereomers. The absolute configuration of one of these diastereomers was determined by X-ray structure analysis. The mixture of cis and trans diastereomers was lithiated by lithium diisopropylamide (LDA) to obtain the trans forms selectively, with the stereoselectivity being determined by NOE experiments.     

Conversion of 4-amino-1H-1,5-benzodiazepine-3-carbonitrile to pyrazolo[3,4-d]pyrimidines,pyrimido[1,6-a]benzimidazole,and pyrazolo[3′,4′:4,5]pyrimido[1,6-a]benzimidazoles

The reactions of multifunctional compounds 2a, b, c, 3a, b and 4a, b which were readily obtained from 4-amino-1H-1,5-benzodiazepine-3-carbonitrile 1 with orthoesters are described, and derivatives of pyrazolo-[3,4-d]pyrimidines 5 , pyrimido[1,6-a]benzimidazole 9 , and pyrazolo[3′,4′:4,5]pyrimido[1,6-a]benzimidazole 10 are synthesized.     

Reactivities of novel [hydroxy(tosyloxy)iodo]arenes and [hydroxy(phosphoryloxy)iodo]arenes for alpha-tosyloxylation and alpha-phosphoryloxylation of ketones

Novel [hydroxy(tosyloxy)iodo]arenes bearing 2-thienyl, 3-thienyl, N-tosyl-4-pyrazolyl, 3-trifluoromethylphenyl, and 3,5-bis(trifluoromethy)phenyl as an aromatic group, and [hydroxy(phosphoryloxy)iodo]arenes bearing N-tosyl-4-pyrazolyl, 3-trifluoromethylphenyl, and 3,5-bis(trifluoromethy)phenyl as an aromatic group, were prepared. alpha-Tosyloxylation and alpha-phosphoryloxylation of ketones with these compounds were carried out, respectively. Their reactivities were compared with that of the parent [hydroxy(tosyloxy)iodo]benzene and [hydroxy(phosphoryloxy)iodo]benzene, respectively, and consequently [hydroxy(tosyloxy)iodo]arenes and [hydroxy(phosphoryloxy)iodo]arenes bearing 3-trifluoromethylphenyl and 3,5-bis(trifluoromethy)phenyl as an aromatic group showed the best reactivity. These new compounds can be used as powerful alpha-tosyloxylation and alpha-phosphoryloxylation reagents, instead of the parent [hydroxy(tosyloxy)iodo]benzene and [hydroxy(phosphoryloxy)iodo]benzene.