Влияние предварительной сжимающей нагрузки на работу, производимую монокристаллами Cu-Al-Ni при взрывном восстановлении деформации памяти формы

The ability of martensitic single crystals Cu 82.5 wt.% - Al 13.5 wt.% - Ni 4.0 to perform work has been investigated. It is shown that weight placed on the crystal is transferred smoothly or by impact during shape memory strain recovery (SMS) Moving depends on the preliminary deformation of the crystal. An influence of the preload on this work is studied. It was found that the transition to the impact mode occurs after preliminary compression of the crystal to the full SMS (~ 9%), when the load is more than twice the stress of the detwinning of martensite. DSC calorimetry showed that after compression to 200–250 MPa and higher sharp narrowing of reverse martensitic transformation (RMT) peak takes place.

Inconsistent reporting of life experiences: What people think and how they explain it?

Assessment of life experiences relies mainly on cross-sectional retrospective design, despite the concerns regarding inconsistent reports. Studies suggest that some individuals change their answers when asked repeatedly, but common opinions underlying this behaviour remain unknown. Our study explored personal perceptions regarding inconsistent reporting and identified associated reasons including individual, experiences-related, and design-related characteristics. Seventy-two individuals, enrolled in a longitudinal study about life experiences, answered a measure about general perceptions and involved reasons. Participants seemed to be aware that inconsistent reporting is a common behaviour, which highly impact on research. A cluster analysis revealed two clusters (i.e., variables involved versus not involved). Most disagreed that sociodemographic variables influence inconsistency, whereas memory, mood, valence, impact, mode of data collection, and interviewer features were pointed as key-variables. Our results suggest that inconsistent reporting is not straightforward and it is probably rooted in a varied and complex set of variables.

Analysis of Self-oscillating Single-acting Hydro-impact System Operational Modes with Two Limiters of Striker Movement

A new property of self-oscillating single-acting hydro-impact systems is considered in this paper – an ability to make strikes in forward and backward directions in presence of two limiters of striker movement without structural changes in device. Mathematical models are presented for system, which includes a flow rate source, a control valve, an impact unit (body frame, striker and spring), an energy accumulator and two limiters. Program for system operational modes (op-modes) simulation is developed and dynamics of specific typical device is numerically investigated. Theoretical oscillograms of its dynamic characteristics and dependencies of integral characteristics on source and impact device parameters are analyzed. At low flow rate multiimpact self-oscillating cycles are obtained, in which the nature of dynamics phenomenon repeats after several striker-limiters interactions. Increase of flow rate leads to single-impact working mode with forward direction of striker movement, then to transition to double-impact mode with forward and backward directions and, further, to single-impact mode with backward direction. Transition boundary points, in which system op-modes changes, are found. Results of this paper can be applied in development of reversible hydro-impact devices (with impacts in forward and backward directions) for mining and construction engineering.

The Effect of the Parameters of a Vibration-Based Impact Mode Piezoelectric Power Generator

This study reports the effects of the parameters of a vibration-based impact mode piezoelectric power generator. First, an evaluation of the effects of the impact parameters, the mass, and the impact velocity is presented. It is found that the output voltage of the piezoelectric device in impact mode is directly proportional to the velocity, whereas the output power is equal to a quadratic function of the same variable. For the same impact momentum, the effect of the velocity in generating a higher peak output is dominant compared with the mass. Second, the vibration-based impact mode piezoelectric power generator is discussed. The experimental results show that a wider operating frequency bandwidth of the output power can be achieved with the preloading configuration. However, regarding magnitude, due to the high velocity of impact, the configuration with a gap between the tip and the piezoelectric device produces a higher output.