97,771 research outputs found
Simulation results of 3D ETS (Episodic Tremor and Slow-slip) asperity-in-matrix model using QDYN earthquake simulator
No full textThis data set contains simulation results of 3D ETS asperity-in-matrix model of Matlab .mat files for
Luo, Y., and Liu, Z. (2021) Fault Zone Heterogeneities Explain Depth-dependent Pattern and Evolution of Slow Earthquakes in Cascadia, Nature Communications.
It is generated by QDYN earthquake simulator (https://github.com/ydluo/qdyn Luo, Y., Ampuero, J. P., Galvez, P., Van den Ende, M., and Idini, B. (2017). QDYN: a Quasi-DYNamic earthquake simulator (v1. 1). Zenodo.(doi: 10.5281/zenodo. 322459).)
1. Uniform Model (10 years, dense output, Uniform_model/)
2. Binary (Bi-modular) Model (4 years, Binary_model/)
3. Linear Model (40 years, dense output, Linear_model/)
4. Comparison of asperity distributions (asp_patttern/):
4.1 (asp_patttern/tri/) - hexagon pattern asperity distribution
4.2 (asp_patttern/sqr/) - rectangular pattern asperity distribution
4.2 (asp_patttern/rnd/) - random asperity distribution
File format: (see details in documents of QDYN)
p - model settings
ot0, ot3d: timeseries outputs
ox0, ox3d: snapshot outputs<br
The Neutrophil/Lymphocyte Ratio Could Predict Noninvasive Mechanical Ventilation Failure in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Retrospective Observational Study [Corrigendum]
No full textSun W, Luo Z, Jin J, Cao Z, Ma Y. Int J Chron Obstruct Pulmon Dis. 2021;16:2267–2277.
The authors have advised the author list on page 2267 is incorrect. The text “Yingmin Ma2” should read “Yingmin Ma1,2”.
The authors apologize for this error
Analysis of ballistic capture in Sun–planet models
No full textAnalysis of ballistic capture orbits in Sun–planet systems is conducted in this paper. This mechanism utilizes purely gravitational forces, and may occur in non-Keplerian regimes. Ballistic capture orbits are generated by proper manipulation of sets of initial conditions that satisfy a simple definition of stability. Six Sun–planet systems are considered, including the inner planets, Jupiter, and Saturn. The role of planets orbital eccentricity, their true anomaly, and mass ratios is investigated. Moreover, the influence of the post-capture orbit in terms of inclination and orientation is also assessed. Analyses are performed from qualitative and quantitative perspective. The quality of capture orbits is measured by means of the stability index, whereas the capture ratio gives information on their statistical occurrence. Some underlying principles on the selection of the dynamical model, the initial true anomaly, and inclination are obtained. These provide a reference for practical cases
Capability of satellite-aided ballistic capture
Get PDFIn this paper we study a special instance of ballistic capture dynamics: the case in which the capture orbit about a planet experiences a close passage to one or more of its natural satellites. The capability of the satellites in improving ballistic capture is assessed. The dynamical framework considers at least the gravitational attractions of the Sun, the planet, and its satellites, all acting on a massless particle. The effect of the satellites is introduced explicitly by modifying a previously developed method, which relies on three-dimensional stable sets and n-body dynamics with precise ephemeris. Once a stability criterium is defined, initial conditions defined over a computational grid are integrated forward and backward. This allows us to classify orbits into different sets. Ballistic capture orbits with prescribed features are generated by manipulating these sets. Two indices, namely the hyperbolic velocity and the stability index, are used to assess the performance of pre- and post-capture portions, respectively. A Pareto frontier is used to extract orbits of practical interest. Case studies are performed in the context of Earth and Jupiter environments. Comparing to the situation with no moons, the satellite-aided ballistic capture can evidently increase the pre-capture energy and post-capture stability, so making it possible to have permanent capture of a particle at zero-cost. This is a desirable feature in mission design
Mars orbit insertion via ballistic capture and aerobraking
Get PDFA novel Mars orbit insertion strategy that combines ballistic capture and aerobraking is presented. Mars ballistic capture orbits that neglect the aerodynamics are first generated, and are distilled from properly computed stable and unstable sets by using a pre-established method. A small periapsis maneuver is implemented at the first close encounter to better submit a post-capture orbit to the aerobraking process. An adhoc patching point marks the transition from ballistic capture to aerobraking, from which an exponential model simulating the Martian atmosphere and a box-wing satellite configuration are considered. A series of apoapsis trim maneuvers are then computed by targeting a prescribed pericenter dynamic pressure. The aerobraking duration is then estimated using a simplified two-body model. Yaw angle tuning cancels the inclination deflections owing to out-of-plane perturbation from the Sun. A philosophy combining in-plane and out-of-plane dynamics is proposed to simultaneously achieve the required semi-major axis and inclination. Numerical simulations indicate that the developed method is more efficient in terms of the fuel consumption, insertion safety, and flexibility when compared with other state-of-the-art insertion strategies
High-Order State Transition Polynomial with Time Expansion Based on Differential Algebra
No full textIn this study, the problem of propagating an initial orbital state around its reference value to a variable final time is addressed. Based on the differential algebra (DA) technique, a high-order state transition polynomial with time expansion (STP-T) method is developed. The STP-T is a high-order Taylor approximation of the final orbital state expanded around the reference initial state and the propagation time. Thus, given the initial displaced orbital state, any state around the reference final time can be efficiently obtained by evaluating the corresponding polynomial. Furthermore, an asynchronous-order scheme for STP-T is presented, which enables the STP-T to have different orders with respect to the variables with different nonlinearity. Besides, the manual derivation and integration of the high-order variational equations is avoided in the DA framework, which makes the order of the polynomial flexible and the method versatile for various dynamics. The simulation results indicate that the STP-T supplies a good approximation of the final state in pure and J2 perturbed Keplerian dynamics, and in a nonlinear relative motion
Complete solution of the Diophantine equation
Get PDFsummary:The triples , , where , satisfy the equation . In this paper it is shown that the same equation has no integer solution with , thus a conjecture put forward by Z. Zhang, J. Luo, P. Z. Yuan (2013) is confirmed
Structure characterization and tribological study of magnetron sputtered nanocomposite nc-TiAlV(N, C)/a-C coatings
Get PDFGrown by reactive unbalanced magnetron sputtering in a mixed N2 and CH4 gaseous medium, heterogeneous nanocomposite coatings in the Ti-Al-V-N-C system show extraordinarily excellent tribological performance of coated machining tools. Using analytical high resolution TEM, EELS, FEG-SEM, XRD, and Raman spectroscopy, this paper reports detailed structural and chemical characterization of the coatings grown at various CH4: N2 ratios. Meanwhile, the mechanical and tribological properties were also measured, including hardness, Young’s modulus, residual stress and the dry-sliding friction and wear at varying environmental humidity. When CH4 gas was introduced in the deposition, the structure of the coatings has been found to experience a change from nano-scale TiAlN-VN multilayer architecture to a complex mixture of columnar grains of nc-TiAlV(N,C)/a-C nanocomposites and inter-column network of sp2-type amorphous carbon. Carbon incorporation and segregation also shows remarkable influence on the columnar growth model by leading to finer grain size. As compared to the carbon-free nitride coating, the nanocomposite coatings showed substantially reduced residual stress owing to the free-carbon precipitation, whereas the coatings maintained comparable hardness to the carbon-free TiAlN/VN. Their tribological properties were found to be strongly dependent on the environment. In humid air at RH > 30%, the coatings showed low friction coefficient less than 0.4 and extremely low wear rate at a scale of ~10-17 m3N-1m-1
A New Exact Algorithm for Single-Commodity Vehicle Routing with Split Pickups and Deliveries
Get PDFWe present a new exact algorithm to solve a challenging vehicle routing problem with split pickups and deliv-
eries, named as the Single Commodity Split Pickup and Split Delivery Vehicle Routing Problem (SPDVRP).
In the SPDVRP, any amount of a product collected from a pickup customer can be supplied to any delivery
customers, and the demand of each customer can be collected or delivered multiple times by the same or
dierent vehicles. The vehicle
eet is homogeneous with limited capacity and maximum route duration. This
problem arises regularly in inventory and routing rebalancing applications, such as in bike-sharing systems,
where bikes must be rebalanced over time such that the appropriate number of bikes and open docks are
available to users. The solution of the SPDVRP requires determining the number of visits to each customer,
the relevant portions of the demands to be collected from or delivered to the customers, and the routing of
the vehicles. These three decisions are intertwined, contributing to the hardness of the problem.
Our new exact algorithm for the SPDVRP is a branch-price-and-cut algorithm based on a pattern-based
mathematical formulation. The algorithm relies on a novel label-setting algorithm used to solve the pricing
problem associated with the pattern-based formulation, where the label components embed reduced cost
functions, unlike those classical components that embed delivered or collected quantities, thus signicantly
reducing the dimension of the corresponding state space. Extensive computational results on dierent classes
of benchmark instances illustrate that the newly proposed exact algorithm solves several open SPDVRP
instances and signicantly improves the running times of state-of-the-art algorithms
Studies of true bugs of Xinjiang, western ChinaILeptopodomorpha: shore bugs (Hemiptera: Heteroptera: Saldidae)
No full textFIGURE 18. Biotope of H. minuta sp. n. in region near lake Lop Nur: bugs occur near ephemeral grassy pools (photo by Yuan Lei).Published as part of Vinokurov, Nikolai N., Luo, Zhaohui & Lü, Zhaozhi, 2012, Studies of true bugs of Xinjiang, western China. I. Leptopodomorpha: shore bugs (Hemiptera: Heteroptera: Saldidae), pp. 51-61 in Zootaxa 3336 on page 58, DOI: 10.5281/zenodo.28132
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