A Diagnostic Study of the Asymmetric Distribution of Rainfall during the Landfall of Typhoon Haitang(2005)

The precipitation during landfall of typhoon Haitang （2005） showed asymmetric structures （left side/right side of the track）. Analysis of Weather Research and Forecasting model simulation data showed that rainfall on the right side was more than 15 times stronger than on the left side. The causes were analyzed by focusing on comparing the water vapor flux, stability and upward motion between the two sides. The major results were as follows： （1） Relative humidity on both sides was over 80%, whereas the convergence of water vapor flux in the lower troposphere was about 10 times larger on the right side than on the left side. （2） Both sides featured conditional symmetric instability [MPV （moist potential vorticity） 〈0], but the right side was more unstable than the left side. （3） Strong （weak） upward motion occurred throughout the troposphere on the right （left） side. The Q vector diagnosis suggested that large-scale and mesoscale forcing accounted for the difference in vertical velocity. Orographic lift and surface friction forced the development of the asymmetric precipitation pattern. On the right side, strong upward motion from the forcing of different scale weather systems and topography caused a substantial release of unstable energy and the transportation of water vapor from the lower to the upper troposphere, which produced torrential rainfall. However, the above conditions on the left side were all much weaker, which led to weaker rainfall. This may have been the cause of the asymmetric distribution of rainfall during the landfall of typhoon Haitang.

OBSERVATIONAL ANALYSIS OF ASYMMETRIC DISTRIBUTION OF CONVECTION ASSOCIATED WITH TROPICAL CYCLONES “CHANCHU” AND “PRAPIROON” MAKING LANDFALL ALONG THE SOUTH CHINA COAST

Observational data of mesoscale surface weather stations and weather radars of Guangdong province are employed to analyze the asymmetric distribution of convection prior to, during and after landfall for tropical cyclones of Chanchu and Prapiroon making landfall on the south China coast in 2006. The results showed that strong convection is located in the eastern and northern sectors of the landfalling Chanchu and Prapiroon, namely in the front and right portions of the TC tracks, for a period of time starting from 12 h prior to landfall to 6 h after it. Their convection also had distinct differences in the vertical direction. The analysis indicated that although the landfall of Chanchu and Prapiroon has the same asymmetric distribution of convection, the causes are not exactly the same. The asymmetric distribution of convection in the case of Chanchu is mainly correlated with the impacts of a strong environmental vertical wind shear, low-level horizontal wind shear, and low-level convergence and divergence. In the case of Prapiroon, however, the asymmetric distribution of convection is mainly associated with the impacts of low-level convergence and divergence.

The Asymmetric Laplace Law for distribution of aluminum contact resistance in spot welding

This paper investigates the distribution of contact resistance of the aluminum alloy in the squeeze stage. A new method of measuring path＇ s resistance is proposed firstly. Contact resistances are calculated accurately by the systems of 5 linear equations and solutions show that three contact resistances are different. The probability density functions of contact resistance in workpiece/workpiece（ W/W） and upper electrode/workpiece（ E/W） show that the curve shape has steeper peak and heavier tail than that of the normal distribution. Non-parameter hypothesis test is performed and the result shows that R2 , R4 reject the normal distribution using chi-square and kolmogoroo statistic D method. Therefore, the Asymmetric Laplace distribution is fitted to empirical distributions and is applied to quantify the influence of random contact resistance. The result illustrates that AL distribution is very close to contact resistance of W/W and upper E/W and normal distribution has some deviation. The paper is helpful to research the initial nugget conditions, weldability and the transient multi-coupling field.

Residual Stress Distribution of Asymmetric Quenching in Al-Zn-Mg-Cu Aluminum Alloy Plate

The residual stress distribution for two strategies of asymmetric quenching in Al-Zn-Mg-Cu aluminum alloy plates has been simulated using the finite element method. The results show that for asymmetric quenching between the upper and lower surfaces, the through-thickness asymmetric quenching residual stress distribution lies between the two distributions corre-sponding to the heat transfer coefficients on the upper and lower surfaces respectively. The surface and central stress magnitudes are equal to the average of the stress magnitudes corresponding to the two heat transfer coefficients. For asymmetric quenching of a single surface, the surface stress distribution is the same as the heat transfer coefficient distribution and the stress magnitude is equal to the stress magnitude corresponding to the average value of the heat transfer coefficients at each location. However, the center quench residual stress distribution is approximately uniform and the stress magnitude is equal to the average of the stress magnitudes corresponding to the maximum and minimum heat transfer coefficients.

Application of the homotopy analysis method to nonlinear characteristics of a piezoelectric semiconductor fiber

Based on the nonlinear constitutive equation,a piezoelectric semiconductor(PSC)fiber under axial loads and Ohmic contact boundary conditions is investigated.The analytical solutions of electromechanical fields are derived by the homotopy analysis method(HAM),indicating that the HAM is efficient for the nonlinear analysis of PSC fibers,along with a rapid rate of convergence.Furthermore,the nonlinear characteristics of electromechanical fields are discussed through numerical results.It is shown that the asymmetrical distribution of electromechanical fields is obvious under a symmetrical load,and the piezoelectric effect is weakened by an applied electric field.With the increase in the initial carrier concentration,the electric potential decreases,and owing to the screen-ing effect of electrons,the distribution of electromechanical fields tends to be symmetrical.

Topp-Leone Odd Fréchet Generated Family of Distributions with Applications to COVID-19 Data Sets

Recent studies have pointed out the potential of the odd Fréchet family(or class)of continuous distributions in fitting data of all kinds.In this article,we propose an extension of this family through the so-called“Topp-Leone strategy”,aiming to improve its overall flexibility by adding a shape parameter.The main objective is to offer original distributions with modifiable properties,from which adaptive and pliant statistical models can be derived.For the new family,these aspects are illustrated by the means of comprehensive mathematical and numerical results.In particular,we emphasize a special distribution with three parameters based on the exponential distribution.The related model is shown to be skillful to the fitting of various lifetime data,more or less heterogeneous.Among all the possible applications,we consider two data sets of current interest,linked to the COVID-19 pandemic.They concern daily cases confirmed and recovered in Pakistan from March 24 to April 28,2020.As a result of our analyzes,the proposed model has the best fitting results in comparison to serious challengers,including the former odd Fréchet model.

Fabrication of long-period fiber gratings by CO_2 laser in fiber under tension

We demonstrate experimentally fabrication of CO2 laser written long-period fiber gratings （LPFGs） in single-mode fiber （SMF） under tension. New transmission dips can be generated due to the frozen-in stress in the fiber under tension. Dynamics analysis of laser writing process is performed to study the mechanism of the grating inscription. Experimental results show that the wavelength shift of new generated resonance dips can shift towards the longer or shorter wavelength with the increase of laser scanning cycles for gratings with different pitches.

Structural jump-diffusion model for pricing collateralized debt obligations tranches

This paper considers the pricing problem of collateralized debt obligations tranches under a structural jump-diffusion model, where the asset value of each reference entity is generated by a geometric Brownian motion and jump with an asymmetric double exponential distribution. Conditioned on the common factor of individual entity, this paper gets the conditional distribution, and further obtains the loss distribution of the whole reference portfolio. Based on the semi-analytic approach, the fair spreads of collateralized debt obligations tranches, i.e., the prices of collateralized debt obligations tranches, are derived.

Generalized Method of Moments and Generalized Estimating Functions Using Characteristic Function

GMM inference procedures based on the square of the modulus of the model characteristic function are developed using sample moments selected using estimating function theory and bypassing the use of empirical characteristic function of other GMM procedures in the literature. The procedures are relatively simple to implement and are less simulation-oriented than simulated methods of inferences yet have the potential of good efficiencies for models with densities without closed form. The procedures also yield better estimators than method of moment estimators for models with more than three parameters as higher order sample moments tend to be unstable.

Basic Functions for Computational Implementation of the Box-Cox Symmetric Class of Distributions

A class of distributions called Box-Cox symmetric was proposed for random variables with asymmetric distributions. This class allows through its structure an interpretation of the parameters in terms of quantiles (in particular, the median), relative dispersion and skewness. This study presents the initial results of the computational development of basic functions of each of the distributions that make up the Box-Cox symmetric class. Four functions have been developed to compose a routine in software R up to now. These functions are related to random numbers generation, probability density function, cumulative distribution function, and quantile function associated to a given probability. Examples of implemented functions were presented. The gamlss routine was used to check the performance of developed functions.

Analysis of Rolling Pressure in Asymmetrical Rolling Process by Slab Method

The plane strain asymmetrical rolling was analyzed using slab method. The contact arc was replaced by parabola, and the constant surface friction status was adopted during the analysis. The deformation area was divided into three zones according to the direction of the friction. Then, the three zones were studied, respectively. A rolling force model and a rolling torque model were developed based on the analysis, and they were used to analyze the influ- ence of asymmetrical rolling factors on deformation area and unit pressure if they had good precision which was determined by comparing the calculated results with the measured ones.

Improved Particle Filter for Non-Gaussian Forecasting-aided State Estimation

Gaussian assumptions of non-Gaussian noises hinder the improvement of state estimation accuracy.In this paper,an asymmetric generalized Gaussian distribution(AGGD),as a unified representation of various unimodal distributions,is applied to formulate the non-Gaussian forecasting-aided state estimation problem.To address the problem,an improved particle filter is proposed,which integrates a near-optimal AGGD proposal function and an AGGD sampling method into the typical particle filter.The AGGD proposal function can approximate the target distribution of state variables to greatly alleviate particle degeneracy and promote precise estimation,through considering both state transitions and latest measurements.For rapid particle generation from the AGGD proposal function,an efficient inverse cumulative distribution function(CDF)sampling method is employed based on the derived approximation of inverse CDF of AGGD.Numerical simulations are carried out on a modified balanced IEEE 123-bus test system.The results validate that the proposed method outperforms other popular state estimation methods in terms of accuracy and robustness,whether in Gaussian,non-Gaussian,or abnormal measurement errors.

Working-in-tandem mechanism of multi-dopants in enhancing electrocatalytic nitrogen reduction reaction performance of carbon- based materials

Developing carbon-based electrocatalysts with excellent N2 adsorption and activation capability holds the key to achieve highly efficient nitrogen reduction reaction(NRR)for reaching its practical application.Here,we report a highly active electrocatalyst--metal-free pyrrolic-N dominated N,S co-doped carbon(pyrr-NSC)for NRR.Based on theoretical and experimental results,it is confirmed that the N and S-dopants practice a working-in-tandem mechanism on pyrr-NSC,where the N-dopants are utilized to create electropositive C sites for enhancing N2 adsorption and the S-dopants are employed to induce electron backdonation for facilitating N2 activation.The synergistic effect of the pyrrolic-N and S-dopants can also suppress the irritating hydrogen evolution reaction,further boosting the NRR performance.This work gives an indication that the combination of two different dopants on electrocatalyst can enhance NRR performance by working in the two tandem steps-the adsorption and activation of N2 molecules,providing a new strategy for NRR electrocatalyst design.

Investigation on Inlet Recirculation Characteristics of Double Suction Centrifugal Compressor with Unsymmetrical Inlet

The inlet recirculation characteristics of double suction centrifugal compressor with unsymmetrical inlet structures were studied in numerical method,mainly focused on three issues including the amounts and differences of the inlet recirculation in different working conditions,the circumferential non-uniform distributions of the inlet recirculation,the recirculation velocity distributions of the upstream slot of the rear impeller.The results show that there are some differences between the recirculation of the front impeller and that of the rear impeller in whole working conditions..In design speed,the recirculation flow rate of the rear impeller is larger than that of the front impeller in the large flow range,but in the small flow range,the recirculation flow rate of the rear impeller is smaller than that of the front impeller.In different working conditions,the recirculation velocity distributions of the front and rear impeller are non-uniform along the circumferential direction and their non-uniform extents are quite different.The circumferential non-uniform extent of the recirculation velocity varies with the working conditions change.The circumferential non-uniform extent of the recirculation velocity of front impeller and its distribution are determined by the static pressure distribution of the front impeller,but that of the rear impeller is decided by the coupling effects of the inlet flow distortion of the rear impeller,the circumferential unsymmetrical distribution of the upstream slot and the asymmetric structure of the volute.In the design flow and small flow conditions,the recirculation velocities at different circumferential positions of the mean line of the upstream slot cross-section of the rear impeller are quite different,and the recirculation velocities distribution forms at both sides of the mean line are different.The recirculation velocity distributions in the cross-section of the upstream slot depend on the static pressure distributions in the intake duct.