Torsion exceptional sheaves on weak del Pezzo surfaces of Type A

We investigate torsion exceptional sheaves on a weak del Pezzo surface of degree greater than two whose anticanonical model has at most $A_n$-singularities. We show that every torsion exceptional sheaf can be obtained from a line bundle on a $(-1)$-curve by acting spherical twist functors successively.Comment: 22 pages. Comments are welcome; v2: typos and statements in section 3 are corrected, other sections remains unchanged; v3: final version, to appear in J. Algebr

Evaluation on crashworthiness and energy absorption of composite light airplane

[[abstract]]The main aim of this study was to explore the safety differences when using aluminum alloy and three different fiber reinforced composites as material for the cockpit and fuselage of light aircraft under crash landing. In accordance with the cockpit reduction amount stipulated by MIL-STD-1290A in which the reducing rates in all directions cannot exceed 15%, this study established the safety zones of impact speeds and impact angles. The overall safety zones of the carbon fiber reinforced composites and glass fiber reinforced composites cockpits were higher than that of the aluminum alloy cockpit by 38.56% and 32.12%, respectively. Among the four different fuselage materials, when carbon fiber reinforced composites was used as the cockpit material, except that the reducing rate for the crashing in the Y direction was slightly higher than the aluminum alloy cockpit, the reducing rate in the X direction and the inclined beam A direction during crashes were less than other materials, and the safety of its overall cockpit was also the most superior to other materials. The energy absorption capability of the aluminum alloy fuselage was better than the fuselages of all composite materials.[[notice]]補正完

Quotient triangulated categories

For a self-orthogonal module $T$, the relation between the quotient triangulated category $D^b(A)/K^b({\rm add} T)$ and the stable category of the Frobenius category of $T$-Cohen-Macaulay modules is investigated. In particular, for a Gorenstein algebra, we get a relative version of the description of the singularity category due to Happel. Also, the derived category of a Gorenstein algebra is explicitly given, inside the stable category of the graded module category of the corresponding trivial extension algebra, via Happel's functor $F: D^b(A) \longrightarrow T(A)^{\mathbb{Z}}{-}\underline{\rm mod}$.Comment: 14 pages. Manu. Math., to appea

Subsampling Cointegration Ranks in Large Systems

In this paper we investigate the possibility of the application of subsampling procedure for testing cointegration relations in large multivariate systems. The subsampling technique is applied to overcome the difficulty of nonstandard distribution and nuisance parameters in testing for cointegration rank without an explicitly formulated structural model. The contribution in this paper is twofold: theoretically this paper shows that the subsampling testing procedure is consistent and has asymptotically power 1;practically this paper demonstrates that the subsampling procedure can be applied to determine the cointegration rank in large scale models, where the standard procedures hits already its limit. For empirical relevant cases our simulation studies show that centered subsampling improves decisively the performance of subsampling test procedure and makes it applicable also for cases when the number of independent stochastic trends are very large.Cointegration, Large Systems, Nonparametric Tests, Subsampling

A time series causal model

Cause-effect relations are central in economic analysis. Uncovering empirical cause-effect relations is one of the main research activities of empirical economics. In this paper we develop a time series casual model to explore casual relations among economic time series. The time series causal model is grounded on the theory of inferred causation that is a probabilistic and graph-theoretic approach to causality featured with automated learning algorithms. Applying our model we are able to infer cause-effect relations that are implied by the observed time series data. The empirically inferred causal relations can then be used to test economic theoretical hypotheses, to provide evidence for formulation of theoretical hypotheses, and to carry out policy analysis. Time series causal models are closely related to the popular vector autoregressive (VAR) models in time series analysis. They can be viewed as restricted structural VAR models identified by the inferred causal relations.Inferred Causation, Automated Learning, VAR, Granger Causality, Wage-Price Spiral

THE TRANSITION PROCESS IN CHINA: AN ECONOMIC DEVELOPMENT PERSPECTIVE

During the last 25 years, the Chinese economy has experienced significant changes: the centrally planned economy has been reformed gradually into a market economy; the traditional agricultural economy is becoming more and more a modern industrial economy. In a dynamic two-sector-two-segment model we demonstrate that the economic reform has changed the industrialization mechanism in China. It released a decentralized industrialization process beside the centrally planned Soviet-type industrialization. This decentralized industrialization is shown to be the ultimate driving force of the transition from plan to market in China.Transition, Economic Reform, Industrialization, the Chinese Economy

Spatial ergodicity and central limit theorems for parabolic Anderson model with delta initial condition

Let $\{u(t\,, x)\}_{t >0, x \in\mathbb{R}}$ denote the solution to the parabolic Anderson model with initial condition $\delta_0$ and driven by space-time white noise on $\mathbb{R}_+\times\mathbb{R}$, and let $p_t(x):= (2\pi t)^{-1/2}\exp\{-x^2/(2t)\}$ denote the standard Gaussian heat kernel on the line. We use a non-trivial adaptation of the methods in our companion papers \cite{CKNP,CKNP_b} in order to prove that the random field $x\mapsto u(t\,,x)/p_t(x)$ is ergodic for every $t >0$. And we establish an associated quantitative central limit theorem following the approach based on the Malliavin-Stein method introduced in Huang, Nualart, and Viitasaari \cite{HNV2018}