Cicada(Tibicen linnei) steers by force vectoring

To change flight direction, flying animals modulate aerodynamic force either relative to their bodies to generate torque about the center of mass, or relative to the flight path to produce centripetal force that curves the trajectory. In employing the latter, the direction of aerodynamic force remains fixed in the body flame and rotations of the body redirect the force. While both aforementioned techniques are essential for flight, it is critical to investigate how an animal balances the two to achieve aerial locomotion. Here, we measured wing and body kinematics of cicada （Tibicen linnei） in flee flight, including flight periods of both little and substantial body reorientations. It is found that cicadas employ a common force vectoring technique to execute all these flights. We show that the direction of the half-stroke averaged aerodynamic force relative to the body is independent of the body orientation, varying in a range of merely 20 deg. Despite directional limitation of the aerodynamic force, pitch and roll torque are generated by altering wing angle of attack and its mean position relative to the center of mass. This results in body rotations which redirect the wing force in the global flame and consequently change the flight traiectorv.

A Nonlinear Representation of Model Uncertainty in a Convective-Scale Ensemble Prediction System

How to accurately address model uncertainties with consideration of the rapid nonlinear error growth characteristics in a convection-allowing system is a crucial issue for performing convection-scale ensemble forecasts.In this study,a new nonlinear model perturbation technique for convective-scale ensemble forecasts is developed to consider a nonlinear representation of model errors in the Global and Regional Assimilation and Prediction Enhanced System(GRAPES)Convection-Allowing Ensemble Prediction System(CAEPS).The nonlinear forcing singular vector(NFSV)approach,that is,conditional nonlinear optimal perturbation-forcing(CNOP-F),is applied in this study,to construct a nonlinear model perturbation method for GRAPES-CAEPS.Three experiments are performed:One of them is the CTL experiment,without adding any model perturbation;the other two are NFSV-perturbed experiments,which are perturbed by NFSV with two different groups of constraint radii to test the sensitivity of the perturbation magnitude constraint.Verification results show that the NFSV-perturbed experiments achieve an overall improvement and produce more skillful forecasts compared to the CTL experiment,which indicates that the nonlinear NFSV-perturbed method can be used as an effective model perturbation method for convection-scale ensemble forecasts.Additionally,the NFSV-L experiment with large perturbation constraints generally performs better than the NFSV-S experiment with small perturbation constraints in the verification for upper-air and surface weather variables.But for precipitation verification,the NFSV-S experiment performs better in forecasts for light precipitation,and the NFSV-L experiment performs better in forecasts for heavier precipitation,indicating that for different precipitation events,the perturbation magnitude constraint must be carefully selected.All the findings above lay a foundation for the design of nonlinear model perturbation methods for future CAEPSs.

Comparison of Constant and Time-variant Optimal Forcing Approaches in El Nio Simulations by Using the Zebiak–Cane Model

Model errors offset by constant and time-variant optimal forcing vector approaches （termed COF and OFV, respectively） are analyzed within the framework of E1 Nifio simulations. Applying the COF and OFV approaches to the well-known Zebiak-Cane model, we re-simulate the 1997 and 2004 E1 Nifio events, both of which were poorly degraded by a certain amount of model error when the initial anomalies were generated by coupling the observed wind forcing to an ocean com- ponent. It is found that the Zebiak-Cane model with the COF approach roughly reproduced the 1997 E1 Nifio, but the 2004 E1 Nifio simulated by this approach defied an ENSO classification, i.e., it was hardly distinguishable as CP-E1 Nifio or EP-E1 Nifio. In hoth E1 Nifio simulations, substituting the COF with the OFV improved the fit between the simulations and obser- vations because the OFV better manages the time-variant errors in the model. Furthermore, the OFV approach effectively corrected the modeled E1 Nifio events even when the observational data （and hence the computational time） were reduced. Such a cost-effective offset of model errors suggests a role for the OFV approach in complicated CGCMs.

Applying Virtual Reality to Molecular Graphics System

Molecular graphics can be thought of as a window to the computer through which the chemist expresses ideas for computational evaluation and receives results in an understandable form. Furthermore, with beautiful graphic images it can give out the realistic molecular model like a real thing in real world.Molecule has various properties including volume, electronic, van der Waals forces, etc. These properties are very important to understand the molecular world. So if the virtual reality tools are used, then the imaginary world can be studied intuitively by touching and feeling a tremendous amount of data.Computational chemistry generates such amount of molecular property data through supercomputing with molecular simulation experiment. One of the objects to investigate the molecular world is to understand the intermolecular interaction such as drug-receptor interaction. Another thing is to measure the geometrical data in molecular architecture. Virtual reality system provides the easiest way to meet these objects. This kind of simple system changes a numerical data set, which is very difficult to deal with, into a visible and understandable data set. Recently two functions of such a system were improved to get an insight into biomolecular interaction. The first one is a real time force generation during navigation in macromolecular environment. An cylindrical arrow shows the magnitude and direction of molecular force. The second one is to see a moIecular vibration such as a concerted motion of the binding site in protein molecule. So one can understand the molecular shape change for drugreceptor docking procedure. But some problems which are difficult to solve still remain.