We present a two-step synthesis process to produce hierarchical ZnO nanoarchitectures that involves the preparation of nanosheet arrays by pyrolysis precursor Zn5(OH)8Cl2 electrodeposited on conductive glass substrates, followed aqueous chemical growth (ACG) dense single-crystalline nanowires surfaces primary nanosheets. The dye-sensitized solar cell (DSSC) based nanowire−nanosheet architectures showed power conversion efficiency 4.8%, which is nearly twice as high DSSC constructed using...

We develop a singular stochastic control model for pricing variable annuities with the guaranteed minimum withdrawal benefit. This benefit promises to return entire initial investment, withdrawals spread over term of contract, irrespective market performance underlying asset portfolio. A contractual rate is set and no penalty imposed when policyholder chooses withdraw at or below this rate. Subject fee, allowed higher than surrender policy instantaneously. explore optimal strategy adopted by...

We propose a dynamic portfolio choice model with the mean-variance criterion for log returns. The yields time-consistent policies and is analytically tractable even under some incomplete market settings. conform conventional investment wisdom (e.g., richer people should invest more absolute amounts of money in risky assets; longer time horizon, proportional amount be invested long-term investment, not short-sell major stock indices whose returns are higher than risk-free rate), provides...

In this paper, we present a wavelet-based despeckling method for synthetic aperture radar images and derive Bayesian wavelet shrinkage factor to estimate noise-free coefficients.To preserve edges during despeckling, apply modified ratio edge detector the original image use obtained information in our framework.Experimental results demonstrate that compares favorably several other methods on test images.

This paper is concerned with the optimality of a trend following trading rule. The idea to catch bull market at its early stage, ride trend, and liquidate position first evidence subsequent bear market. We characterize phases markets mathematically using conditional probabilities given up date stock prices. optimal buying selling times are in terms sequence stopping determined by two threshold curves. Numerical experiments conducted validate theoretical results demonstrate how they perform...

ABSTRACT We propose a tractable model of dynamic investment, spinoffs, financing, and risk management for multidivision firm facing costly external finance. Our analysis formalizes the following insights: (i) Within‐firm resource allocation is based not only on divisions' productivity, as in winner‐picking models, but also their risk; (ii) firms may voluntarily spin off productive divisions to increase liquidity; (iii) diversification can reduce value low‐liquidity states, it increases...

A continuous-time Markowitz's mean-variance portfolio selection problem is studied in a market with one stock, bond, and proportional transaction costs. This singular stochastic control problem, inherently finite time horizon. Via series of transformations, the turned into so-called double obstacle well-studied physics PDE literature, featuring two time-varying free boundaries. The boundaries, which define buy, sell, no-trade regions, are proved to be smooth time. turn characterizes optimal...

This paper is concerned with numerical solutions to a singular stochastic control problem arising from continuous-time portfolio selection proportional transaction costs. The associated value function governed by variational inequality gradient constraints. We propose penalty method deal the constraints and employ finite difference discretization. Convergence analysis presented. also show that standard can be applied in case of single risky asset where reduced inequality. Numerical results...

Multilevel image segmentation is time-consuming and involves large computation. The firefly algorithm has been applied to enhancing the efficiency of multilevel segmentation. However, in some cases, easily trapped into local optima. In this paper, an improved (IFA) proposed search thresholds. IFA, order help fireflies escape from optima accelerate convergence, two strategies (i.e., diversity strategy with Cauchy mutation neighborhood strategy) are adaptively chosen according different...

Abstract We study a dynamic mean‐variance portfolio optimization problem under the reinforcement learning framework, where an entropy regularizer is introduced to induce exploration. Due time–inconsistency involved in criterion, we aim learn equilibrium policy. Under incomplete market setting, obtain semi‐analytical, exploratory, policy that turns out follow Gaussian distribution. then focus on mean return model and propose algorithm find Thanks thoroughly designed iteration procedure our...

Mitophagy is the lysosome-dependent degradation of damaged and dysfunctional mitochondria, which closely associated with H2O2-related redox imbalance pathological processes. However, development fast-responding highly sensitive reversible fluorescent probes for monitoring mitochondrial H2O2 dynamics still lacking. Herein, we report a probe (M-HP) that enables real-time imaging imbalance. In vitro studies demonstrated M-HP had rapid response high sensitivity to H2O2/GSH cycle, detection limit...

The binomial tree method, first proposed by Cox, Ross, and Rubinstein [Journal of Financial Economics, 7 (1979), pp. 229--263], is one the most popular approaches to pricing options. By introducing an additional path-dependent variable, such methods can be readily extended valuation In this paper, using numerical analysis notion viscosity solutions, we present a unifying theoretical framework show uniform convergence for European/American options, including arithmetic average geometric...

This paper presents a frame-level hybrid framework for modeling MPEG-4 and H.264 multi-layer variable bit rate (VBR) video traffic. To accurately capture long-range-dependent short-range-dependent properties of VBR sequences, we use wavelets to model the distribution I-frame sizes simple time-domain P/B frame sizes. However, unlike previous studies, analyze successfully both inter-GOP (group pictures) <i xmlns:mml="http://www.w3.org/1998/Math/MathML"...

This paper concerns continuous-time optimal investment and the consumption decision of a constant relative risk aversion (CRRA) investor who faces proportional transaction costs finite time horizon. In no-consumption case, it has been studied by Liu Loewenstein [Review Financial Studies, 15 (2002), pp. 805–835] Dai Yi [J. Differential Equations, 246 (2009), 1445–1469]. Mathematically, is singular stochastic control problem whose value function satisfies parabolic variational inequality with...

Iron salt-modified biochar has been widely used to remove Cr(VI) pollution due the combination of generated iron oxides and biochar, which can bring positive charge rich redox activity. However, there are few comprehensive studies on methods modifying with different salts. In this study, two salt (FeCl3 Fe(NO3)3) modification were prepare Fe-modified materials for removing in simulated groundwater environment. It was revealed by systematic characterization that FeCl3@BC prepared via FeCl3...

Capital gains taxation has important implications for investors’ portfolio choice decisions. To explore these implications, we develop a continuous time investment and consumption model with capital tax, Epstein–Zin recursive utility, regime switching. We find that various factors, such as tax rate, risk aversion, interest stock return, volatility, jointly affect optimal allocation, whereas intertemporal substitution does not. In switching market, investors may trade or stop trading purely...

Most existing portfolio choice models ignore the prevalent periodic market closure and fact that volatility is significantly higher during trading periods. We find difference across nontrading periods change optimal strategies. In addition, we demonstrate numerically transaction costs can have a first-order effect on liquidity premia largely comparable to empirical findings. Moreover, this increases in difference, which supported by our analysis. This paper was accepted Jerome Detemple, finance.

This paper is concerned with the optimality of a trend following trading rule. The underlying market modeled like bull-bear switching in which drift stock price switches between two states: uptrend (bull market) and down (bear market). We consider case when mode not directly observable model process as hidden Markov chain. continuation our earlier study reported Dai et al. [Dai M, Zhang Q, Zhu Q (2010) Trend under regime-switching model. SIAM J. Fin. Math. 1:780–810] where rule obtained...