Plastic Flow Modeling of Ti-5 Al-2 Sn-2 Zr-4 Mo-4 Cr Alloy at Elevated Temperatures and High Strain Rates

The true stress-sWain relationships of Ti-5A1-2Sn-2Zr-4Mo-4Cr（TC17） alloy with a wide range of strain rates were investigated by tmiaxial quasi-static and dynamic compression tests, respectively. Quasi- static compression tests were carried out with Instron 8874 test machine, while dynamic compression tests were performed with the split Hopkinson pressure bar （SHPB） which was installed with heating device and synchro- assembly system. The dynamic mechanical behaviors tests of TC17 were carded out from room temperature to 800 ℃ at intervals of 200 ℃ and at high sWain rates （5 500-1 9200 s-l）. The stress-strain curves considering temperature-sWain rate coupling actions were obtained. The Johnson-Cook constitutive model was developed through data fitting of the stress-sWain curves. The material constants in the developed constitutive model can be determined using isothermal and adiabatic stress-strain curves at different strain rates. The Johnson-Cook constitutive model provided satisfied prediction of the plastic flow stress for TC17 alloy.

The stress-velocity relationship of twinning partial dislocations and the phonon-based physical interpretation

The dependence of dislocation mobility on stress is the fundamental ingredient for the deformation in crystalline materials. Strength and ductility, the two most important properties characterizing mechanical behavior of crystalline metals, are in general governed by dislocation motion. Recording the position of a moving dislocation in a short time window is still challenging, and direct observations which enable us to deduce the speed-stress relationship of dislocations are still missing. Using large-scale molecular dynamics simulations, we obtain the motion of an obstacle-free twinning partial dislocation in face centred cubic crystals with spatial resolution at the angstrom scale and picosecond temporal information. The dislocation exhibits two limiting speeds: the first is subsonic and occurs when the resolved shear stress is on the order of hundreds of megapascal. While the stress is raised to gigapascal level, an abrupt jump of dislocation velocity occurs, from subsonic to supersonic regime. The two speed limits are governed respectively by the local transverse and longitudinal phonons associated with the stressed dislocation, as the two types of phonons facilitate dislocation gliding at different stress levels.

Learning Dynamic Causal Relationships Among Sugar Prices

In this paper, we are interested in exploring the dynamic causal relationships among two sets of three variables in different quarters. One set is futures sugar closing price in Zhengzhou futures exchange market （ZC）, spot sugar price in Zhengzhou （ZS） and futures sugar closing price in New York futures exchange market（NC） and the other includes futures sugar opening price in Zhengzhou （ZO）, ZS and NC. For each quarter, we first use Bayesian model selection to obtain the optimal causal graph with the highest BD scores and then use Bayesian model averaging approach to explore the causal relationship between every two variables. From the real data analysis, the two conclusions almost coincide, which shows that the two methods are practical.

Discussion about the Triple Foundational Relationship between Intellect,Emotion,and Willing from the Perspective of the Phenomenology of Consciousness

There are at least three foundational relationships between the three conscious acts of intellect,emotion,and willing.Section 2 covers the structural foundational relationship(Brentano and Husserl in his early period):all conscious acts are intentional and can be divided into objectifying(intuition and representation)and non・objectifying acts(emotion and willing).Because a non-objectifying act cannot constitute an object,things must be based on objectifying acts and the object constituted by the latter;in this sense,a non-objectifying act is rooted in an objectifying one.Section 3 explains the genetic foundational issue with consciousness(Husserl in his later period,Scheier,and Heidegger):the stream of consciousness has its earliest origins and follows a process where it gradually unfolds.The earliest origin is the intentional willing,followed by nonintentional feelings,and,finally,the representation and thinking of willing.Intentional activity taking place afterward must be based on the conscious activity that has come already.Section 4 points out that,apart from the two aforementioned kinds of foundational relationships(i.e.structural and genetic),a third foundational relationship(i.e.dynamic)can also be found between the conscious acts of intellect,emotion,and willing in the Consciousness-only school(a Buddhist tradition in the East).In a continuous activity,the foundational relationship between the three aspects of intellect,emotion,and willing always remains encased in dynamic changes,and the change of primary and secondary roles(i.e.a change in the foundational relationship)could happen at any time.From this perspective,one can explain and resolve the confrontation and conflicts between the two former foundational relationships.

A Universal Equipment for Biaxial Stretching of Polymer Films

A biaxial stretching equipment was designed and constructed to enable fundamental studies of the relationship between film processing conditions and structures of oriented film products. With programmable drive motors and scissorlike mechanism, all stretching modes, including uniaxial stretching with constant and free width, simultaneous and sequential biaxial stretching, can be applied to a square-shaped sheet. Parameters related to film stretching manufacturing, such as temperature, draw ratio and stretching speed can be set independently to meet the requirement of different polymers. The force information during stretching is recorded by two miniature tension sensors in two directions independently, which can monitor the mechanical stimulus and stress response. Using this equipment, experiments are conducted to investigate the influence of stretching parameters on the structure of polypropylene films, which provides an effective method to tailor the processing conditions to obtain the films with desired properties.