The problems of optimizing the trajectory motion of the first stage of an aerospace system according to the criterion of the maximum of the final mass are considered. The control is the angle of ...attack and thrust of the engines. Control optimization is carried out on the trajectory section from the point of bringing the first stage to the launch area until the motion parameters required for separation of the space stage are reached. The Pontryagin’s maximum principle is used to determine optimal control programs. The solution of the problem without restrictions on the modes of motion is carried out using the example of acceleration and climb of the first stage of the RASCAL aerospace system. A method is proposed for determining approximate optimal control in a problem with a limitation on the altitude range of the engines with separate optimization of the active and passive sections and the search for the optimal point of their coupling. Changes in control program, trajectory, and fuel consumption are discussed when limiting the maximum flight altitude in the active section.
In 1928, Dirac published an equation
that combined quantum mechanics and special relativity. Negative-energy solutions to this equation, rather than being unphysical as initially thought, represented ...a class of hitherto unobserved and unimagined particles-antimatter. The existence of particles of antimatter was confirmed with the discovery of the positron
(or anti-electron) by Anderson in 1932, but it is still unknown why matter, rather than antimatter, survived after the Big Bang. As a result, experimental studies of antimatter
, including tests of fundamental symmetries such as charge-parity and charge-parity-time, and searches for evidence of primordial antimatter, such as antihelium nuclei, have high priority in contemporary physics research. The fundamental role of the hydrogen atom in the evolution of the Universe and in the historical development of our understanding of quantum physics makes its antimatter counterpart-the antihydrogen atom-of particular interest. Current standard-model physics requires that hydrogen and antihydrogen have the same energy levels and spectral lines. The laser-driven 1S-2S transition was recently observed
in antihydrogen. Here we characterize one of the hyperfine components of this transition using magnetically trapped atoms of antihydrogen and compare it to model calculations for hydrogen in our apparatus. We find that the shape of the spectral line agrees very well with that expected for hydrogen and that the resonance frequency agrees with that in hydrogen to about 5 kilohertz out of 2.5 × 10
hertz. This is consistent with charge-parity-time invariance at a relative precision of 2 × 10
-two orders of magnitude more precise than the previous determination
-corresponding to an absolute energy sensitivity of 2 × 10
GeV.
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The photon-the quantum excitation of the electromagnetic field-is massless but carries momentum. A photon can therefore exert a force on an object upon collision
. Slowing the translational motion of ...atoms and ions by application of such a force
, known as laser cooling, was first demonstrated 40 years ago
. It revolutionized atomic physics over the following decades
, and it is now a workhorse in many fields, including studies on quantum degenerate gases, quantum information, atomic clocks and tests of fundamental physics. However, this technique has not yet been applied to antimatter. Here we demonstrate laser cooling of antihydrogen
, the antimatter atom consisting of an antiproton and a positron. By exciting the 1S-2P transition in antihydrogen with pulsed, narrow-linewidth, Lyman-α laser radiation
, we Doppler-cool a sample of magnetically trapped antihydrogen. Although we apply laser cooling in only one dimension, the trap couples the longitudinal and transverse motions of the anti-atoms, leading to cooling in all three dimensions. We observe a reduction in the median transverse energy by more than an order of magnitude-with a substantial fraction of the anti-atoms attaining submicroelectronvolt transverse kinetic energies. We also report the observation of the laser-driven 1S-2S transition in samples of laser-cooled antihydrogen atoms. The observed spectral line is approximately four times narrower than that obtained without laser cooling. The demonstration of laser cooling and its immediate application has far-reaching implications for antimatter studies. A more localized, denser and colder sample of antihydrogen will drastically improve spectroscopic
and gravitational
studies of antihydrogen in ongoing experiments. Furthermore, the demonstrated ability to manipulate the motion of antimatter atoms by laser light will potentially provide ground-breaking opportunities for future experiments, such as anti-atomic fountains, anti-atom interferometry and the creation of antimatter molecules.
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Two new genera and four new species of Berothidae (
Berothone
gen. nov.,
Krokhathone parva
gen. et sp. nov.,
K. tristis
gen. et sp. nov.,
Sinosmylites karatavicus
sp. nov., and
S. auliensis
sp. nov) ...are described from the Upper Jurassic of Karatau (Kazakhstan).
Sinosmylites hotgoricus
sp. nov. is described from the Upper Jurassic of Khoutiyn-Khotgor (Mongolia). Intraspecific variation of Jurassic berothids, quantitative composition of the berothid fauna of Karatau, and records of the family from Jurassic and Lower Cretaceous deposits are discussed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Cretapsychops skywalkeri
sp. nov., a new species of the family Psychopsidae (Neuroptera), is described from the Upper Jurassic of Karatau locality (Kazakhstan). This is the first record of
...Cretapsychops
Jepson et al., 2009 from the Mesozoic of Central Asia; before now, this genus was only reported from the Lower Cretaceous of England and the Middle Jurassic of China. The forewings of the new species have a contrasting pattern of dark stripes, which probably served as disruptive coloration, reducing the risk of predation by insectivorous pterosaurs or coelurosaurs.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The subject of the research. The research focuses on the legal prohibitions and obligations for convicts to imprisonment fixed in the norms of legislation and in subordinate regulatory legal acts ...adopted in accordance with it.The purpose of the research is to confirm or refute the hypothesis that there is a current discrepancy between the content of the legal responsibilities of convicts and the goals of the penal enforcement such as rehabilitation and preventing of the commission of new crimes, their social essence and legal nature.Methods of the research. The research uses retrospective analysis of legislation in the field of execution of criminal punishment in the form of imprisonment, as well as analysis and synthesis of legal literature and empirical research data. To confirm the conclusions of the research authors use sociological survey of 364 citizens and 221 employees of penal institutions located in the Siberian Federal District (the cities of Kemerovo, Novokuznetsk, Novosibirsk, Tomsk, Omsk) aged from 18 to 73 years.The main results of the research and the scope of their application. On the basis of retrospective analysis of the norms of penal enforcement (formerly correctional labor) law, which establish the penitentiary duties of convicts, the goals and objectives of penal enforcement legal regulation, the results of an empirical study, it is concluded that some of the responsibilities (including prohibitions) of convicts in criminal enforcement law do not have a strict scientific explanation. Their establishment is dictated not only by the need to achieve the purposes of convicts rehabilitation and preventing the commission of new crimes, but also to solve a number of other tasks that do not fit into the existing concept of the execution of punishment in the form of imprisonment and violate the balance between the "punitive" and "correctional-preventive" content of punishment. These include responsibilities that: are a relic of the Soviet socialist society; provide administrative, economic, managerial and other activities of penal institutions; unreasonably "seem" to be an effective way to rehabilitate convicts and prevent the commission of new crimes by both convicts and other persons.Conclusions. The solution of the mentioned problems in the light of the development of penal enforcement policy in general and of its legislative form in particular is possible in several ways. The first one is that the legal responsibilities of the convicts to imprisonment should be reviewed (excluded, or the content should be changed), taking into account their real impact on the achievement of the goals established by law (or change the latter) and the constantly changing rules and traditions of the human society. The second one is to change the goals of the penal enforcement legislation to its current (and possibly future) norms. The third "middle ground" way consists in simultaneous changing of the goals of the penal enforcement legislation and of the legal responsibilities of convicts in the direction of expanding the dispositive principles of criminal enforcement legal regulation, excluding certain of their responsibilities and prohibitions and expanding their rights.
Sol–gel derived organo-silicate hybrid coatings preloaded with organic corrosion inhibitors have been developed in order to provide active corrosion protection when integrity of the coating is ...compromised. The incorporation of organic corrosion inhibitors into hybrid coatings has been achieved as a result of physical entrapment of the inhibitor within the coating material at the stage of film formation and cross-linking. Entrapped corrosion inhibitor becomes active in corrosive electrolyte and can slowly diffuse out of the host material. To ensure continuing delivery of the inhibitor to corrosion sites and long-term corrosion protection, a sustained release of the inhibitor is achieved by a reversible chemical equilibrium of either ion-exchange of the inhibitor with the coating material or through cyclodextrin-assisted molecular encapsulation. Several organic compounds, such as mercaptobenzothiazole, mercaptobenzimidazole, mercaptobenzimidazolesulfonate, and thiosalicylic acid, have been selected to evaluate the effectiveness of these two approaches. Corrosion protection performance of the coatings on aluminum alloy 2024-T3 has been examined using electrochemical methods including scanning vibrating electrode technique, potentiodynamic scan, and electrochemical impedance spectroscopy.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The task of optimizing the space vehicle combined orbital plane change maneuver with the aim of maximizing its final mass is considered in the paper. Burst of power is used for the vehicles exit from ...the initial low earth orbit and subsequent re-entry. Starting from atmospheric entry till the end of the orbital plane change with the entry in the final orbit the angle of attack, the air-path bank angle and the fuel-flow rate are used as controls. Limitations for the angle of attack, fuel-flow rate, adiabatic recovery temperature, longitudinal and vertical load factor are introduced. The successive linearization method is used to determine the optimal control programs. Solving the optimization task is exemplified by a hypothetical space vehicle. The results of modeling space vehicle motion are presented. The changes in the determined aerodynamic (angle of attack and air-path bank angle) and motion (fuel-flow rate) controls with increasing the angle of orbital plane change are discussed with and without account of the key limitation on the modes of motion maximum adiabatic recovery heating temperature.
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