Transverse Thrust Research Articles

Extension of frozen orbits and Sun-synchronous orbits around terrestrial planets using continuous low-thrust propulsion

Frozen orbits and Sun-synchronous orbits are useful in exploration of terrestrial planets’ surface and atmosphere with a view to future human exploration. This work therefore develops novel orbits around terrestrial planets using continuous low-thrust propulsion to enable one new and unique investigations of the planets. This paper considers the use of continuous acceleration by solar electric propulsion, to achieve artificial frozen orbits and artificial Sun-synchronous orbits around terrestrial planets. These artificial orbits are similar to natural frozen orbits and Sun-synchronous orbits around Mercury, Venus, the Earth, and Mars, and the orbital parameters can be designed arbitrarily with the help of continuous low-thrust control. The control strategies to achieve the artificial orbits take into account $J_{2}$ , $J_{3}$ , and $J_{4}$ perturbations of terrestrial planets. It is proved that the control strategies minimize characteristic velocity. Relevant formulas are derived, and numerical results are presented. For the natural frozen orbits, the arguments of periapsis are about 270° for Mercury, Venus, and Mars, whereas about 90° for the Earth. By exerting both radial and transverse thrusts simulation shows that the control acceleration and characteristic velocity of the artificial frozen orbit around Mercury are the smallest among these plants. The characteristic velocity within one orbital period for Mercury is only 0.0089 m/s. The natural Sun-synchronous orbits exist around the Earth and Mars, but not around Mercury and Venus. By offsetting the perturbation acceleration in norm direction, the control acceleration and characteristic velocity of the artificial Sun-synchronous orbit around Mars are less than those of the others. The characteristic velocity within one orbital period is only 18.0885 m/s for the artificial Sun-synchronous orbit around Mars. The relationships between the control thrusts and the primary orbital parameters of the artificial orbits around other terrestrial planets are always similar to those around the Earth. Finally, one constellation of the artificial frozen orbit and the artificial Sun-synchronous orbit is designed by using the multiobjective evolutionary algorithm based on decomposition (MOEA/D), in which a Gaussian process is used to build a surrogate model in lieu of the expensive problem. Simulation shows that the control scheme effectively extends the orbital parameters’ selection ranges of the two types of artificial orbits around terrestrial planets, compared with the natural frozen orbit and Sun-synchronous orbit. The optimization result of the constellation orbits around Mars shows that the optimization framework is effective.

Factorization and resummation for transverse thrust

We analyze transverse thrust in the framework of Soft Collinear Effective Theory and obtain a factorized expression for the cross section that permits resummation of terms enhanced in the dijet limit to arbitrary accuracy. The factorization theorem for this hadron-collider event-shape variable involves collinear emissions at different virtualities and suffers from a collinear anomaly. We compute all its ingredients at the one-loop order, and show that the two-loop input for next-to-next-to-leading logarithmic accuracy can be extracted numerically, from existing fixed-order codes.

Electric sail control mode for amplified transverse thrust

The electric solar wind sail produces thrust by centrifugally spanned high voltage tethers interacting with the solar wind protons. The sail attitude can be controlled and attitude maneuvers are possible by tether voltage modulation synchronous with the sail rotation. Especially, the sail can be inclined with respect to the solar wind direction to obtain transverse thrust to change the osculating orbit angular momentum. Such an inclination has to be maintained by a continual control voltage modulation. Consequently, the tether voltage available for the thrust is less than the maximum voltage provided by the power system. Using a spherical pendulum as a model for a single rotating tether, we derive analytical estimations for the control efficiency for two separate sail control modes. One is a continuous control modulation that corresponds to strictly planar tether tip motion. The other is an on–off modulation with the tether tip moving along a closed loop on a saddle surface. The novel on–off mode is introduced here to both amplify the transverse thrust and reduce the power consumption. During the rotation cycle, the maximum voltage is applied to the tether only over two thrusting arcs when most of the transverse thrust is produced. In addition to the transverse thrust, we obtain the thrusting angle and electric power consumption for the two control modes. It is concluded that while the thrusting angle is about half of the sail inclination for the continuous modulation it approximately equals to the inclination angle for the on–off modulation. The efficiency of the on–off mode is emphasized when power consumption is considered, and the on–off mode can be used to improve the propulsive acceleration through the reduced power system mass.

Glauber gluons and multiple parton interactions

We show that for hadronic transverse energy E T in hadron-hadron collisions, the classic Collins-Soper-Sterman (CSS) argument for the cancellation of Glauber gluons breaks down at the level of two Glauber gluons exchanged between the spectators. Through an argument that relates the diagrams with these Glauber gluons to events containing additional soft scatterings, we suggest that this failure of the CSS cancellation actually corresponds to a failure of the ‘standard’ factorisation formula with hard, soft and collinear functions to describe E T at leading power. This is because the observable receives a leading power contribution from multiple parton interaction (or spectator-spectator Glauber) processes. We also suggest that the same argument can be used to show that a whole class of observables, which we refer to as MPI sensitive observables, do not obey the standard factorisation at leading power. MPI sensitive observables are observables whose distributions in hadron-hadron collisions are disrupted strongly by the presence of multiple parton interactions (MPI) in the event. Examples of further MPI sensitive observables include the beam thrust B , + and transverse thrust.

Measurement of charged-particle event shape variables in inclusive(s)=7 TeVproton-proton interactions with the ATLAS detector

The measurement of charged-particle event shape variables is presented in inclusive inelastic pp collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the LHC. The observables studied are the transverse thrust, thrust minor and transverse sphericity, each defined using the final-state charged particles' momentum components perpendicular to the beam direction. Events with at least six charged particles are selected by a minimum-bias trigger. In addition to the differential distributions, the evolution of each event shape variable as a function of the leading charged particle transverse momentum, charged particle multiplicity and summed transverse momentum is presented. Predictions from several Monte Carlo models show significant deviations from data.

Influence of Lateral Interval on Aerodynamics Characteristics of Crossing Vehicles

The investigations about vehicle crossing process mainly use numerical simulation methods and, moreover, the relevant investigation is quite less. In this study, a three- dimensional fluid simulation model was established. By moving mesh technique, the three- dimensional transient simulation for vehicle crossing process was finished. The aerodynamics characteristics of vehicle crossing process with different lateral interval distances were analyzed. The analytical results show that the smaller the lateral interval distance, the more the transverse thrust between two vehicles during the crossing process. During the whole crossing process, the lateral force shows itself with repulsion in the beginning and attraction in the end. When the lateral interval distance of crossing is very small, the air disturbance due to crossing not only makes large affection to the lateral force but also influence obviously the positive pressure area of the front car bodywork.

Measurement of event shapes inpp¯collisions ats=1.96 TeV

A study of event shape observables in proton-antiproton collisions at 1.96 TeV is presented. The data for this analysis were recorded by the CDF II detector at the Tevatron collider. The variables studied are the transverse thrust and thrust minor, both defined in the plane perpendicular to the beam direction. The observables are measured using energies from unclustered calorimeter cells. In addition to studies of the differential distributions, we present the dependence of event shape mean values on the leading jet transverse energy. Data are compared with pythia Tune A and to resummed parton level predictions that were matched to fixed order results at NLO accuracy (NLO+NLL). Predictions from pythia Tune A agree fairly well with the data. However, the underlying event contributes significantly to these observables, making it difficult to make direct comparisons to the NLO+NLL predictions, which do not account for the underlying event. To overcome this difficulty, we introduce a new observable, a weighted difference of the mean values of the thrust and thrust minor, which is less sensitive to the underlying event, allowing for a comparison with NLO+NLL. Both pythia Tune A and the NLO+NLL calculations agree well within the 20% theoretical uncertainty with the data for this observable, indicating that perturbative QCD successfully describes shapes of the hadronic final states.

Forward–backward correlations and event shapes as probes of minimum-bias event properties

Measurements of inclusive observables, such as particle multiplicities and momentum spectra, have already delivered important information on soft-inclusive (“minimum-bias”) physics at the Large Hadron Collider. In order to gain a more complete understanding, however, it is necessary to include also observables that probe the structure of the studied events. We argue that forward–backward (FB) correlations and event-shape observables may be particularly useful first steps in this respect. We study the sensitivity of several different types of FB correlations and two event-shape variables—transverse thrust and transverse thrust minor—to various sources of theoretical uncertainty: multiple parton interactions, parton showers, color (re)connections, and hadronization. The power of each observable to furnish constraints on Monte Carlo models is illustrated by including comparisons between several recent, and qualitatively different, Pythia 6 tunes, for pp collisions at $\sqrt{s}=900~\mbox{GeV}$ .

유공판의 좌굴강도에 관한 연구

The aim of the present study is to investigate the buckling strength of plates and stiffened panels with opening under transverse thrust and shear actions. It is observed that the existing design formulation for critical-buckling strength of plates are not valid for perforated plates, because the current design formulation trends can significantly overestimate or underestimate the load-carrying capacity of plates when plates have large opening and/or are thick. A series of eigen value and elastic.plastic large deflection finite element analyses are carried out with varying the aspect ratio of plate, the opening size and location on plate until and after the ultimate strength is reached. Based on the results obtained from the present study, closed-form design formulations for the elastic buckling strength of plates and stiffened panels with opening are derived. The derived design formulations are considered plasticity correction of the material and verified by experimental tests and results of nonlinear finite element computations.

New data on the stratigraphy and depositional environment for Upper Jurassic and Lower Cretaceous deposits of the Stolbovoi Island (New Siberian Islands)

The section of Mesozoic terrigenous deposits over 1200 m thick has been described, and a new geological map of the Stolbovoi Island southern half has been compiled. The inference has been made that the sedimentary sequence represents a single uniform turbidite complex, which is indivisible into lithological units and which does not show transition to shallow-marine facies either in the visible foot section or visible roof section. The complex accumulated in the foreland basin emerged on the margin of the Novosibirsk-Chukchi continental block during the Anyuian orogeny. The presence of upper Volgian deposits (Upper Jurassic) with a visible thickness of 640 m, Berriasian (Ryazanian) deposits about 100-m thick, and lower Valanginian deposits with a visible thickness of ∼200 m has been established on the basis of identification of fossils represented by remains of bivalve mollusks (the genus Buchia). Finds of upper Volgian buchias in the southeastern part of the island are inconsistent with field geological observations of the sequence of deposits. Paleontological data acquired for the island southern part suggest the presence of a transverse thrust fault, along which upper Volgian rocks were thrust over lower Neocomian rocks. The possibility of another interpretation of the data has also been considered. The correlation of the Buchia Beds of the Stolbovoi Island, Nordvik Peninsula, the basin of the Anyui River, and northern California has been carried out. The inference about a close relationship between the biota of the Stolbovoi Island and the North Pacific paleobiogeographic realm has been drawn.

조합하중을 받는 연속보강판의 좌굴 및 붕괴거동 평가

압축하중 및 횡하중의 조합하중을 받는 연속 보강판넬의 좌굴강도 및 최종강도의 평가는 선체구조 안정성을 재고하는데 아주 중요한 요소이다. 예를들면, 선박의 공창 상태에서 선체외판은 수압하중에 의해서 파생되는 횡방향 면내 압축하중과 선체외판에 작용하는 횡하중은 대표적인 하중 성분이다. 지금까지의 대부분의 연구 결과들은 실험테스트 및 이론석인 접근 그리고 수치계산 방법에 의해서 수행되었으며, 단일 판 또는 보강판의 조합하중에 대한 많은 업적들이 있다. 그러나, 이들 중 대부분의 연구는 종방향 면내 압축하중과 횡하중에 의한 연구결과가 대부분이며, 횡방항 면내 압축하중과 횡하중에 대한 결과들은 상대적으로 많지가 않다. 게다가 이전의 연구들은 주고 네변 단순지지된 판부재를 고려하였으나, 실제의 구조를 고려해보면, 횡방향 프레임과 종방향 거더들이 교차되어 있는 보강 판넬 구조이다. 본 연구는, 3척의 실적선에서 얻은 이중저 판넬 모델을 적용하고, 횡하중의 크기를 변수로 한 탄소성대변형 유한요소해석을 수행하였다. 이러한 여러 가지 수치 해석을 통하여, 횡하중의 크기 변화에 대한 영향과 횡방향 압축하중이 작용하는 붕괴 매커니즘에 대해서 고찰하였다. Estimation of the buckling and ultimate strength of a continuous stiffened plate subjected to combined transverse compression and lateral pressure is of high importance to ensure the safety of ship structures, particularly for the bottom plating under a deep draft condition For example, bottom plating of bulk carriers is subjected to transverse thrust caused by the bending of double bottom structure and the direct action of pressure on the side shells. Most of experimental tests, theoretical approach and numerical researches have been performed on the buckling and ultimate strength behaviour of plates or stiffened plates under combined compression and lateral pressure. With regard to stiffened panels, however, most of studies have been concerned with the load conditions of combined longitudinal thrust and lateral pressure, while fewer studies have been performed for the combined transverse thrust and lateral pressure. In addition, the previous researches are mainly concerned with an isolated rectangular plate simply supported along the all edges, whereas actual ship plating is continuous across the transverse frames and heavy girders. In the present paper, a series of elastoplastic large deflection FEA on a continuous stiffened plate is performed and then clarify the characteristic of collapse mode and explain the effect of transverse compression.

High-efficiency piezoelectric single-phase uni-polar ultrasonic actuators with a notched PZT back disc

Disclosed herein is a high efficiency piezoelectric single phase uni-polar supersonic actuator which is composed of an upper back disc, a PZT plate an electrode, a lower back disc, a pivotal bolt and a fixing nut. The PZT plate and its electrode are interposed between the upper and the lower back discs, and the whole actuator unit is supported and fixed with the pivotal bolt and the nut combination by passing the bolt coaxially through the center of the actuator unit. The parametric output variation of the actuator is carried out by an asymmetrical structure due to varying number, size and location of notches, or a variety of notch and screw combination made on the upper back disc such that after the electrode is energized, the actuator produces an unbalanced periodic axial or transverse thrust force to drive a rotor installed on the pivotal bolt above the upper back disc. The maximum rotating speed of the rotor may reach up to above 3000 rpm.

Estimation of ultimate strength of continuous stiffened panel under combined transverse thrust and lateral pressure Part 1: Continuous plate

A simplified method to estimate the ultimate strength of a continuous plate, typical in ship bottom plating, subjected to combined transverse thrust and lateral pressure is developed. A series of elastic/elastoplastic large deflection finite element analysis (FEA) of a continuous plate supported along the lines of longitudinal stiffeners and transverse frames is performed. Attention is focused on the effect of a continuity of plating on its buckling and ultimate strengths, while the previous studies are mainly concerned with an isolated plate. Based on the FEA results, a set of formulae has been derived for the estimation of the ultimate strength of a continuous plate under combined transverse thrust and lateral pressure. An increase of elastic buckling strength and a change in the collapse mode from a simply supported mode to a clamped mode are considered as an effect of a continuity of plating. It has been proven from a comparison with FEA that the proposed formulae give very accurate predictions of the ultimate strength.

Estimation of ultimate strength of continuous stiffened panel under combined transverse thrust and lateral pressure Part 2: Continuous stiffened panel

A set of design formulae to estimate the ultimate strength of a continuous stiffened panel subjected to combined transverse thrust and lateral pressure is presented, extending the basic idea proposed for a continuous plate in Part-1 study. The effect of plate/stiffener interaction on the elastic buckling strength of local plate panel is introduced in the formulation as well as the effect of continuity of plating. The overall collapse of stiffeners under lateral pressure is included in the possible failure modes. It has been proven from a comparison with FEA results that the proposed formulae give a good prediction of the ultimate strength of a continuous stiffened panel.

The Motion of a Material Point in a Newtonian Field under the Action of Equiangular Thrust

The problems of investigation and optimization of the motion of spacecraft are extensively discussed in the literature. Nevertheless, in many cases a large variety of qualitative characteristics of their motion and of the form of their trajectories are still unclear. In this paper we consider a plane equiangular acceleration of a spacecraft both in a Newtonian field and in its absence (at a large distance from the center of attraction). The general equation of a trajectory of plane acceleration is presented with the introduction of a new variable, an index of an exponent, which allows one to obtain convenient solutions at different values of the time-independent angle of inclination of the vector of thrust to the spacecraft's radius vector (i.e., when equiangular acceleration takes place). Asymptotic solutions are constructed and an interesting fact is revealed. Namely, it is shown that when the center of attraction exists or is absent, for all initial conditions the trajectories appearing at the above equiangular acceleration of a material point tend to the standard logarithmic spirals at a large distance from the center. Specifically, when the value of transverse (perpendicular to the radius vector) thrust is constant, there appears a logarithmic spiral with an angle of inclination to the radius vector equal to 35.264°. Different forms of the trajectory of equiangular acceleration of spacecraft at a low thrust are also studied. The results obtained can be useful for the investigation and choice of optimum space trajectories.

Next-to-leading order calculation of three-jet observables in hadron-hadron collisions

The production of three jets in hadron-hadron collisions is the first complex process which allows us to define a branch of variables in order to make more precise measurements of the strong coupling and the parton distribution function of the proton. This process is also suitable for studying the geometrical properties of the hadronic final state at hadron colliders. This requires a next-to-leading order prediction of the three-jet observables. In this paper we describe the theoretical formalism of such a calculation with sufficient detail. We use the dipole method to construct a Monte Carlo program for calculating three-jet observables at next-to-leading order accuracy. We present a theoretical prediction for inclusive and exclusive cross sections and for some relevant event shape variables such as the transverse thrust, transverse jet broadening, and ${E}_{t3}$ variable.

Estimation of Ultimate Strength of Continuous Stiffened Plate under Combined Thrust and Lateral Pressure

The authors proposed a set of closed-form simple formulae to estimate ultimate strength of a continuous stiffened plate under combined longitudinal thrust, parallel to stiffener direction, and lateral pressure. This paper extends the application of the formulae to biaxial thrust condition based on a series of elastoplastic large deflection FE analyses. It was found from FEA that the ultimate strength of a continuous stiffened plate under transverse thrust is significantly higher than that of a continuous unstiffened plate simply-supported along stiffener lines because of a stiffener's torsional stiffness. It was also found that there exist two fundamental failure modes; one is local failure mode of plate between stiffener under predominantly transverse thrust and the other is over-all failure mode of stiffened plate under predominantly longitudinal thrust, and that the ultimate strengths corresponding to the respective failure modes can be estimated rather independently, with little interactions. Based on these observations, a set of simple ultimate strength formulae has been derived, and their validity has been confirmed through a comparison with FEA results.

Buckling/Ultimate Strength of Perforated Rectangular Plate under Thrust (2nd Report)

Series of elastic eigenvalue analyses and elastoplastic large deflection analyses were performed to investigate into the influence of perforation on the buckling/ultimate strength of rectangular plate subjected to uni-axial and bi-axial thrust. It has been found that : (1) Beyond the ultimate strength, plastic deformation is concentrated around the opening, and elastic unloading takes place in the remaining part in case of long plate subjected to longitudinal thrust.(2) Beyond the ultimate strength, plastic mechanism of a roof mode developes in case of long plate subjected to transverse thrust.(3) Ultimate strength interaction relationship is derived for bi-axial compression, and it was found that general yielding at the perforated cross-section affects the shape of the interaction curve.Simple formulas are proposed to evaluate the elastic buckling strength of a perforated plate under uni-axial thrust. These formulas are used to evaluate the ultimate strength, which showed good correlations with the FEM results.

Buckling/Ultimate Strength of Perforated Rectangular Plate under Thrust

A series of elastoplastic large deflection analyses was performed to investigate into the influence of perforation on the buckling and ultimate strength of rectangular plate under uni-axial thrust. It has been found that : (1) When the plate is subjected to longitudinal thrust, collapse mode varies depending on the aspect ratio of the plate and sometimes differs from the elastic buckling mode.(2) When the plate is subjected to transverse thrust, collapse mode is fundamentally the same regardless of the aspect ratio and is almost the same as the elastic buckling mode.(3) Simple formulas are proposed to evaluate the ultimate strength of a perforated plate under uni-axial thrust both in longitudinal and transverse directions. The evaluated values of the ultimate strength showed good correlations with the FEM results.

Longitudinal and Transverse Thrust

New shape functions for the lateral deflection of rectangular plate elements for the Idealized Structural Unit Method (ISUM) are developed. First, the collapse behaviour of rectangular plates under longitudinal and transverse thrust is studied by elastoplastic large deflection FEM and the characteristics of the collapse modes are highlighted. Based on these characteristic deflection modes, new lateral shape functions for the large ISUM elements are assumed and implemented. Comparisons with FEM results show the applicability and good accuracy of these new ISUM elements. The importance of shape functions simulating the collapse mode accurately is demonstrated by comparing the new formulation with a previous one and by examining the influence of two yield functions.