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Search Results: 1 - 10 of 50218 matches for " Ping Sun "
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Solid Launcher Dynamical Analysis and Autopilot Design
Ping Sun
International Journal of Image, Graphics and Signal Processing , 2011,
Abstract: The dynamics of a small solid launch vehicle has been investigated. This launcher consists of a liquid upper stage and three fundamental solid rocket boosters aligned in series. During the ascent flight phase, lateral jets and grid fins are adopted by the flight control system to stable the attitude of the launcher. The launcher is a slender and aerodynamically unstable vehicle with sloshing tanks. A complete set of six-degrees-of-freedom dynamic models of the launcher, incorporation its rigid body, aerodynamics, gravity, sloshing, mass change, actuator, and elastic body, is developed. Dynamic analysis results of the structural modes and the bifurcation locus are calculated on the basis of the presented models. This complete set of dynamic models is used in flight control system design. A methodology for employing numerical optimization to develop the attitude filters is presented. The design objectives include attitude tracking accuracy and robust stability with respect to rigid body dynamics, propellant slosh, and flex. Later a control approach is presented for flight control system of the launcher using both State Dependent Riccati Equation (SDRE) method and Fast Output Sampling (FOS) technique. The dynamics and kinematics for attitude stable problem are of typical nonlinear character. SDRE technique has been well applied to this kind of highly nonlinear control problems. But in practice the system states needed in the SDRE method are sometimes difficult to obtain. FOS method, which makes use of only the output samples, is combined with SDRE to accommodate the incomplete system state information. Thus, the control approach is more practical and easy to implement. The resulting autopilot can provide stable control systems for the vehicle.
Mott-Hubbard Scenario for the Metal-Insulator Transition in the Two Dimensional Electron Gas
Ping Sun
Physics , 2006,
Abstract: By comparing the responses to an in-plane magnetic field near the metal-insulator transition (MIT), we find that the observed MIT in Si MOSFETs can be described by the non-perturbative Mott-Hubbard scenario. Interrelations between independent measurables are uncovered and confirmed by replotting the experimental data. A universal critical energy scale vanishing at the MIT is extracted from the experimental data and the critical exponent found.
A probabilistic approach to enumeration of Gessel walks
Sun Ping
Mathematics , 2009,
Abstract: We consider Gessel walks in the plane starting at the origin $(0, 0)$ remaining in the first quadrant $i, j \geq 0$ and made of West, North-East, East and South-West steps. Let $F(m; n_1, n_2)$ denote the number of these walks with exact $m$ steps ending at the point $(n_1, n_2)$, Petkov\v{s}ek and Wilf posed several analogous conjectures similar to the famous Gessel's conjecture. We establish a probabilistic model of Gessel walks which is concerned with the problem of vicious walkers. This model helps us to obtain the linear homogeneous recurrence relations with binomial coefficients for both $F(n+k+r;n+k-r,n)$ and $F(n+2k; n, 0)$. Precisely, $\frac{n! k! (n+k+1)!}{(2n+2)!} F(2n+2k;0,n)$ is a polynomial with all integer coefficients which leading term is $2^{3k-2} n^{2k-2}$, and $\frac{k! (k+1)!}{n+1} F(n+2k;n,0)$ is a polynomial with all integer coefficients which leading term is $n^{2k-1}$. Hence two conjectures of Petkov\v{s}ek and Wilf are solved.
Enumeration of standard Young tableaux of shifted strips with constant width
Ping Sun
Mathematics , 2015,
Abstract: Let $g_{n_1,n_2}$ be the number of standard Young tableau of truncated shifted shape with $n_1$ rows and $n_2$ boxes in each row. By using of the integral method this paper derives the recurrence relations of $g_{3,n}$, $g_{n,4}$ and $g_{n,5}$ respectively. Specially, $g_{n,4}$ is the $(2n-1)$-st Pell number.
A probabilistic approach for enumeration of certain Young tableaux
Ping Sun
Statistics , 2013,
Abstract: In this paper we establish an order statistics model of Young tableaux. Multiple integration over nested simplexes is applied to the enumeration of Young tableaux. A brief proof of Frobenius-Young's and Aitken's formulas is given. Partially standard Young tableaux and special truncated shapes including tableaux with a hole are discussed, the associated product formulas are given.
Golden Ratio estimate of success probability based on one and only sample
Sun Ping
Statistics , 2012,
Abstract: This paper proposes iterative Bayesian method to estimate success probability based on unique sample. The procedure is replacing the distribution characteristic of prior with Bayes estimate on the every iteration until they coincide. Iterative Bayes estimate is generally independent of hyperparameters. For binomial, Poisson, exponential and normal model, iterative limit is shown to be MLE in case the expectation of conjugate prior is replaced respectively. Particularly, suppose success appears in one and only trial, while the mode of triangle prior is replaced iterative Bayesian method gives $1/\phi \approx 0.618$ ($\phi$ is Golden Ratio) as the estimate of success probability $p$, this result reveals the truth of Golden Ratio from the point of statistics. Furthermore, under triangle prior the unique sample $X$ from binomial model $B(n,p)$ is considered. Existence and uniqueness of iterative Bayes estimator $\hat{p}_{IB}$ for parameter $p$ is given.
Histological and immunohistochemical features of the spleen in persistent polyclonal B-cell lymphocytosis closely mimic splenic B-cell lymphoma
Ping Sun, Ridas Juskevicius
Diagnostic Pathology , 2012, DOI: 10.1186/1746-1596-7-107
Abstract: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/5329558967545656 webcitePersistent polyclonal B-cell lymphocytosis (PPBL) is a rare clinically benign lymphoproliferative disorder first described by Gordon et al. in 1982 [1]. To date, around 200 cases worldwide have been reported in literature. PPBL is characterized by chronic mild-to-moderate peripheral polyclonal lymphocytosis of B cell origin as evidenced by flow cytometry and variable number of atypical binucleated lymphocytes present on peripheral blood film. The total lymphocyte count is not always elevated in all patients. Due to the hallmark presence of binucleated lymphocytes, this entity is also called B-cell lymphocytosis with binucleated lymphocytes. The majority of patients also demonstrate polyclonal increase in serum IgM. It is most frequently reported in young or middle-aged female smokers [1-6]. Most patients present with mild nonspecific symptoms, such as weakness and fatigue. Mild splenomegaly is a single most frequently reported clinical finding, present in about 10% of patients according to the largest case series [2]. Massive splenomegaly has been only rarely reported in the literature. As most patients have an indolent clinical course and peripheral lymphocytosis is sometimes absent, this condition is likely under-recognized. PPBL resembles malignant lymphoproliferative disorder in many aspects, both morphologically and at the molecular/cytogenetic levels. In addition to the hallmark atypical lymphocytes, the bone marrow of these patients sometimes shows intrasinusoidal distribution of B lymphocytes resembling marrow involvement by splenic marginal zone lymphoma [7]. We here report histological and immunohistochemical features of the spleen in a young female with PPBL who underwent splenectomy due to progressive splenomegaly on her 6th annual follow-up. Very recently, Italian investigators Del Giudice et al. described similar histopathologi
Youth tobacco use cessation: 2008 update
Steve Sussman, Ping Sun
Tobacco Induced Diseases , 2009, DOI: 10.1186/1617-9625-5-3
Abstract: Tobacco use is the most prevalent lifestyle-related cause of death worldwide [1,2]. Investigation of the prevalence of a regular pattern of tobacco use is illuminating. Daily cigarette smoking prevalence in the United States increases from approximately 4% among 12 year olds, to 8% among 16 year olds, 12% among 18 year olds, 15% among 20 year olds, and levels off among 26 year olds at 22%, and then drops by 4% among older age groups [3]. A similar pattern of regular smoking develops among youth in other countries, with some variation in the age range and steepness in increase [4]. The relatively steep daily smoking inflexion curve evident during the teen years supports the assertion that teen tobacco use cessation programming is needed among the world's youth [5] (also see http://www.globaltreatmentpartnership.org/treatment_case.html webcite, accessed on 12-20-07). In addition, internationally approximately 60%–85% of young tobacco users are likely to have made at least one quit attempt and failed [6-12]. It appears that youth do want to quit tobacco use, and most appear unable to quit on willpower alone [13].There have been 8 systematic reviews of the teen smoking cessation literature thus far. First, Sussman, Lichtman, Ritt, and Pallonen [14] evaluated 34 programs, 17 smoking cessation trials and 17 smoking prevention trials for their impact on cessation of cigarette smoking. Sussman [15] provided an enlarged review of 66 cessation trials (which included single-subject designs), and 17 studies of self-initiated quitting. McDonald et al. [16] provided a re-review of the Sussman [15] study. Garrison et al. [17] reviewed 6 studies of relatively rigorous designs. Backinger et al. [18] did a qualitative review of prevention and cessation programs.Then, Sussman, Sun, & Dent [10] completed the first formal meta-analysis of 48 studies, which included both experimental and quasi-experimental designs. Shortly thereafter Grimshaw & Stanton [19] provided a 2006 Cochrane meta-
Ecological engineering land treatment systems──A new development in China
Gong Ping,Sun Tieheng
环境科学学报(英文版) , 1996,
Abstract: Ecologicalengineeringlandtreatmentsystems──AnewdevelopmentinChina¥GongPing;SunTieheng(InstituteofAppliedEcology,ChineseAcadem...
Multiple nonnegative solutions for BVPs of fourth-order difference equations
Sun Jian-Ping
Advances in Difference Equations , 2006,
Abstract: First, existence criteria for at least three nonnegative solutions to the following boundary value problem of fourth-order difference equation Δ4x(t-2) = a(t)f(x(t)),t ∈ [2, T], x(0) = x(T + 2) = 0, Δ2x(0) = Δ2x(T) = 0 are established by using the well-known Leggett-Williams fixed point theorem, and then, for arbitrary positive integer m, existence results for at least 2m-1 nonnegative solutions are obtained.
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