Showing papers by "Yang Gao published in 2007"
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TL;DR: The International Linear Collider (ILC) is a 200-500 GeV center-of-mass high-luminosity linear electron-positron collider, based on 1.3 GHz superconducting radio-frequency (SCRF) accelerating cavities.
Abstract: The International Linear Collider (ILC) is a 200-500 GeV center-of-mass high-luminosity linear electron-positron collider, based on 1.3 GHz superconducting radio-frequency (SCRF) accelerating cavities. The ILC has a total footprint of about 31 km and is designed for a peak luminosity of 2x10^34 cm^-2 s^-1. The complex includes a polarized electron source, an undulator-based positron source, two 6.7 km circumference damping rings, two-stage bunch compressors, two 11 km long main linacs and a 4.5 km long beam delivery system. This report is Volume III (Accelerator) of the four volume Reference Design Report, which describes the design and cost of the ILC.
55 citations
TL;DR: In this paper, a biomimetic drill and sampler subsystem is designed as a penetrator instrument based on the working mechanism of a wood wasp ovipositor to sample beneath the sterile layer for biomarker detection.
Abstract: Due to ultraviolet flux to the surface layers of most solar system bodies, future astrobiological research is increasingly seeking to conduct subsurface penetration, drilling and sampling to detect chemical signature of extant or extinct life. To seek a compact solution to this issue, we present a micro-penetrator concept (mass < 10 kg) that is suited for planetary deployment and in situ investigation of chemical and physical properties. To draw inspiration from nature, a biomimetic drill and sampler subsystem is designed as a penetrator instrument based on the working mechanism of a wood wasp ovipositor to sample beneath the sterile layer for biomarker detection. One of the major limitations of sampling in relatively low gravity environments (such as asteroids, Mars, etc) is the need for high axial force when using conventional drills. The ovipositor drill is proposed to address this limitation by applying a novel concept of reciprocating motion that requires no external force. It is lightweight (0.5 kg), driven at low power (3 W), and able to drill deep (1-2 m). Tests have shown that a reciprocating drill is feasible and has the potential of improving drill efficiency without receiving any external force. As part of the European space agency (ESA) project on bionics and space system design [1], this study provides a conceptual design of the micro-penetrator targeted for a near earth asteroid mission. With bionics-enabling technology, the overall penetration/drilling/sampling system provides a small, light and energy efficient solution to in situ astrobiological studies, which is crucial for space exploration. Such a micro-penetrator can be used for exploration of terrestrial-type planets or other small bodies of the solar system with a moderate level of modifications.
50 citations
01 Aug 2007
49 citations
TL;DR: In this article, a two-valve-reciprocating motion was proposed for a bio-inspired rotary drill for low gravity environments, which requires no reactive external force.
Abstract: It is widely acknowledged that the next significant challenge in planetary exploration is to be able to drill deeply (two meters seems the most scientifically valuable and the most technologically reasonable) into the surface of solar system bodies for chemical or physical data. Major limitation of using conventional rotary drills in low gravity environments (such as Mars, asteroids, comet, etc) is the need for high axial force, which suffers from big overhead mass, buckling problem, and power hungriness. Though drills using percussive motion may operate in low mass and power, the drilling rate is generally slow. Drawing inspiration from nature for a lightweight and energy efficient solution, we propose a novel drilling method based on the working mechanism of wood wasp ovipositors. The bio-inspired drill requires no reactive external force by applying two-valve-reciprocating motion. The proposed bio-inspired system indicates enhanced utility that is critical for space missions where premium is placed on mass, volume and power. Biological systems are similarly constrained making biomimetic technology uniquely suited and advantageous as a model of miniaturized systems. As a result of the European Space Agency (ESA) project on bionics and space system design [Ellery, 2005], this paper presents a conceptual design of the bio-inspired drill. Lab-based experiments have shown that the two-valve-reciprocating drilling method is feasible and has potential of improving drill efficiency without any additional overhead force or mass.
34 citations
TL;DR: In this paper, the generalized Stroh formalism is used to solve boundary value problems of holomorphic vector functions in a given region. And the same procedure can be used to deal with the elastic problems for 2D and 3D quasicrystals.
Abstract: By means of the generalized Stroh formalism, two-dimensional (2D) problems of one-dimensional (1D) quasicrystals (QCs) elasticity are turned into the boundary value problems of holomorphic vector functions in a given region. If the conformal mapping from an ellipse to a circle is known, a general method for solving the boundary value problems of holomorphic vector functions can be presented. To illustrate its utility, by using the necessary and sufficient condition of boundary value problems of holomorphic vector functions, we consider two basic 2D problems in 1D QCs, that is, an elliptic hole and a rigid line inclusion subjected to uniform loading at infinity. For the crack problem, the intensity factors of phonon and phason fields are determined, and the physical sense of the results relative to phason and the difference between mechanical behaviors of the crack problem in crystals and QCs are figured out. Moreover, the same procedure can be used to deal with the elastic problems for 2D and three-dimensional (3D) QCs.
23 citations
TL;DR: In this paper, a refined theory of rectangular curved beams is derived by using Papkovich-Neuber (shortened form P-N) solution in polar coordinate system and Lur'e method without ad hoc assumptions.
Abstract: Through generalizing the method developed by the refined theory of straight beams, a refined theory of rectangular curved beams is derived by using Papkovich-Neuber (shortened form P-N) solution in polar coordinate system and Lur'e method without ad hoc assumptions. It is shown that the displacements and stresses of the beam can be represented by four displacement functions. For the beam under surface loads, the approximate governing differential equations are derived directly from the refined beam theory and are almost the same as those of other well-known theoretical models. To illustrate the application of the beam theory developed, a pure bending curved beam is examined, which indicates that the stress expressions derived are an exact solution and are consistent with the results gained by exact beam theory of elasticity.
19 citations
TL;DR: In this article, the reciprocal theorem and the general solution for one-dimensional hexagonal quasicrystals (QCs) were applied to obtain the appropriate stress and mixed boundary conditions accurate to all order for plates of general edge geometry and loadings.
Abstract: For plate bending in one-dimensional (1D) hexagonal quasicrystals (QCs), the reciprocal theorem and the general solution for QCs media are applied in a novel way to obtain the appropriate stress and mixed boundary conditions accurate to all order for plates of general edge geometry and loadings. Through generalizing the method developed by Gregory and Wan, a set of necessary conditions on the edge-data for the existence of a rapidly decaying solution is established. The prescribed data must satisfy these conditions in order that they should generate a decaying state. When a set of stress edge-data or mixed edge-data is imposed on the plate edge, these decaying state conditions for the case of axisymmetric deformation of 1D hexagonal QC plates are derived explicitly. They are then used for the correct formulation of boundary conditions for the plate theory solution (or the interior solution). Furthermore, in the absence of phonon–phason fields coupling effect, corresponding necessary conditions for the case of transversely isotropic elastic plates are derived subsequently, and their isotropic elastic counterparts are also obtained.
16 citations
TL;DR: In this article, a refined theory of transversely isotropic beams is proposed on the basis of the classical elasticity theory, and the beam displacements and stresses of the beam can be represented by the angle of rotation and the deflection of the neutral surface.
Abstract: The refined theory of transversely isotropic beams is proposed on the basis of the classical elasticity theory. By using E-L solution and Lur'e method, the refined theory provides the solutions of transversely isotropic beams without ad hoc assumptions. Exact solutions, including a fourth-order part and a transcendental part, are obtained for beams with homogeneous boundary conditions, whereas approximate solutions are derived for beams under transverse surface loadings by dropping terms of high order. It is shown that the displacements and stresses of the beam can be represented by the angle of rotation and the deflection of the neutral surface. In this paper, separate discussions are given to the cases in which characteristic roots are distinct or equal to each other. To the authors' knowledge, the latter has not been covered in the literature. To illustrate the application of the beam theory developed, three examples are examined: a cantilever beam under end loading, a simply supported beam under uniform loading, and a cantilever beam under linear loading. Results show that the refined theory of transversely isotropic beams can be degenerated into that of isotropic beams by omitting anisotropic terms.
16 citations
TL;DR: In this article, a refined plate theory is derived by using Biot's solution of thermoelasticity and the Lur'e method without ad hoc assumptions, and the exact equations and solutions for the plate under anti-symmetrical transverse loadings and temperature distribution are derived directly from the refined plate theories.
Abstract: The problem of deducing two-dimensional theory from three-dimensional theory for a thermoelastic isotropic body is investigated. Based on thermoelasticity theory, the refined plate theory is derived by using Biot's solution of thermoelasticity and Lur'e method without ad hoc assumptions. For the homogeneous boundary conditions, the exact equations and solutions are derived and the equations can be decomposed into four governing differential equations: the biharmonic equation, the shear equation, the transcendental equation and the temperature equation. Moreover, the approximate equations and solutions for the plate under anti-symmetrical transverse loadings and temperature distribution are derived directly from the refined plate theory. By omitting coupling effect and higher-order terms, the refined plate theory can be degenerated into other well-known elastic and thermoelastic theoretical models.
13 citations
14 Jun 2007
TL;DR: The Moon provides a unique record of processes affecting evolution of terrestrial planets in early Solar System history as mentioned in this paper, including internal processes of geological evolution and external processes caused by the environment (e.g. meteorite flux, interplanetary dust density, solar wind flux and composition, galactic cosmic ray flux).
Abstract: It has been 35 years since the last human presence on the Moon. Since then, our knowledge of the Solar System has expanded immeasurably, bringing us up against questions that are impossible to answer on Earth. There is now a global renewed interest in returning to the Moon, driven by the demands of science and as a stepping-stone for human exploration of the Solar System. The Moon provides a unique record of processes affecting evolution of terrestrial planets in early Solar System history (the first Gyr or so). This includes internal processes of geological evolution (e.g. differentiation and the first formation of a crust) and external processes caused by the environment (e.g. meteorite flux, interplanetary dust density, solar wind flux and composition, galactic cosmic ray flux) that are not as easily accessible anywhere else in our solar system.
12 citations
TL;DR: Gao et al. as discussed by the authors applied the reciprocal theorem and P-N solution in a novel way to obtain the appropriate stress and mixed boundary conditions accurate to all order for beam bending problem.
TL;DR: In this paper, the reciprocal theorem and the general solution are applied in a novel way to obtain the appropriate stress and mixed boundary conditions accurate to all order for axisymmetric bending and stretching of a circular plate when stress or mixed conditions are imposed on the plate edge.
Abstract: For plate bending and stretching problems in two-dimensional (2D) dodecagonal quasi-crystal (QC) media, the reciprocal theorem and the general solution for QCs are applied in a novel way to obtain the appropriate stress and mixed boundary conditions accurate to all order. The method developed by Gregory and Wan is used to generate necessary conditions which the prescribed data on the edge of the plate must satisfy in order that it should generate a decaying state within the plate; these decaying state conditions are obtained explicitly for axisymmetric bending and stretching of a circular plate when stress or mixed conditions are imposed on the plate edge. They are then used for the correct formulation of boundary conditions for the interior solution. For the stress data, our boundary conditions coincide with those obtained in conventional forms of plate theories. More importantly, appropriate boundary conditions with a set of mixed edge-data are obtained for the first time. Furthermore, the corresponding necessary conditions for transversely isotropic elastic plate are obtained directly, and their isotropic elastic counterparts are also obtained.
TL;DR: In this paper, the authors derived the exact governing differential equations and solutions for the plate, which consist of four governing equations and four solutions for each of them, up to the second-order terms.
Abstract: Based on thermoelastic theory, various two-dimensional equations and solutions for plane problems have been deduced systematically and directly from thick plate theory by using Biot's solution and Lur'e method without ad hoc assumptions. These equations and solutions can be used to construct the refined theory for the plane problems. In the case of homogeneous boundary conditions, the exact governing differential equations and solutions for the plate are derived, which consist of four governing differential equations. It is important note that the refined theory is consistent with the decomposition theorem by Gregory. In the case of non-homogeneous boundary conditions, the approximate governing differential equations and solutions for the plate are accurate up to the second-order terms. The correctness of the stress assumptions in the classic plane stress problems is revised.
TL;DR: In this article, a decomposition theorem of rectangular beams is presented and the general state of stress of beams can be decomposed into two parts: the interior state and the Papkovich-Fadle state (shortened form the P-F state).
TL;DR: In this article, the authors investigated the pure penguin process using the QCD factorization approach to calculate hadronic matrix elements to the alpha(s) order in some well-known NP models and showed that the NP contributions in R-parity conserved SUSY models and 2HDMs are not enough to make the branching ratios of B -> pi phi as large as their experimental upper bounds.
TL;DR: In this paper, necessary conditions for axisymmetric deformation of a transversely isotropic piezoelectric circular plate when stress and electric displacement conditions are imposed on the plate edge are derived explicitly, which are then used for the formulation of boundary conditions for the plate theory solution.
TL;DR: In this article, the decomposition of a bending magnetoelastic beam without transverse surface loadings can be decomposed into three parts: the interior state, the Papkovich-Fadle state (in shortened form the P-F state) and the magnetic state.
Abstract: The decomposed form of an isotropic elastic plate is extended to a bending magnetoelastic beam with free faces, and the corresponding decomposition theorem is presented. It is shown that the stress state of the magnetoelastic beam without transverse surface loadings can be decomposed into three parts: the interior state, the Papkovich-Fadle state (in shortened form the P-F state) and the magnetic state. Based on the three new lemmata, a rigorous mathematical proof of the decomposition theorem is given concisely and directly, which is independent of the Papkovich-Fadle eigenfunction expansion of biharmonic functions. In the proof course, some basic mathematical methods are used only, so the proof is more convenient for being understood. More importantly, these three states correspond to the three equations derived in the refined theory of magnetoelastic beams: the fourth-order equation, the transcendental equation and the magnetic equation, respectively. Therefore, this work virtually proves the consistency between the decomposition theorem and the refined theory of bending magnetoelastic beams.
TL;DR: In this paper, the authors studied the non-uniqueness of the Boussinesq-Galerkin solution and discussed the validity of Cheng, and Barrett and Ellis' assumptions.
01 Oct 2007
TL;DR: In this paper, a GEM-TPC prototype was designed and constructed successfully; the performance of the prototype has been studied; some of the test result using cosmic-ray is presented in this paper.
Abstract: The TPC read out by GEM detector has many advantages over the traditional ones read out by MWPC (Multi- Wire Proportional Counter). It is a very promising candidate for the central tracking system of International Linear Collider (ILC). In our lab, a GEM-TPC prototype was designed and constructed successfully; the performance of the prototype has been studied; some of the test result using cosmic-ray is presented in this paper.
01 Dec 2007
TL;DR: The UK has an active lunar science community eager to support (robotic) lunar exploration as discussed by the authors, however, these interests have been eclipsed by the drive to Mars, demonstrated by the Vision for Space Exploration in the USA, the evolving Global Exploration Partnership, and new lunar missions from Europe, Japan, China and India.
Abstract: Returning to the Moon has been advocated by a number of planetary scientists in order to answer several key scientific questions. The UK has an active lunar science community keen to support (robotic) lunar exploration. However, for several years, these interests have been eclipsed by the drive to Mars. Recently there is a renewed global interest in the Moon, demonstrated by the Vision for Space Exploration in the USA, the evolving Global Exploration Partnership, and new lunar missions from Europe, Japan, China and India. The ESA Aurora programme may also broaden its focus to embrace the Moon as well as Mars - realising that many of the major technical challenges that are faced by Mars missions could be de-risked by relatively inexpensive and timely lunar precursors. Surrey Satellite Technology Ltd. (SSTL) and Surrey Space Centre (SSC) have been preparing a 'smallsat' approach to achieving a low-cost lunar mission for more than a decade - including various activities, such as Phase B study of LunarSat funded by ESA and a current hardware contribution to the Chandrayaan-1 mission. With the recent successes in GIOVE-A, TOPSAT & BEIJING-1, alongside participation in Aurora & Chandrayaan-1, Surrey has developed capabilities for providing affordable engineering solutions to space exploration. In 2006, SSTL/SSC was funded by the UK Particle Physics and Astronomy Research Council (PPARC) (now included within the UK Science & Technology Facilities Council) to undertake a study on low-cost lunar mission concepts that could address key scientific questions. This paper presents some major results from this study (Phipps and Gao, 2006) and provides preliminary definitions of two down-selected mission proposals. Copyright IAF/IAA. All rights reserved.