The effect on lower spine muscle activation of walking on a narrow beam in virtual reality

To what extent do people behave in immersive virtual environments as they would in similar situations in a physical environment? There are many ways to address this question, ranging from questionnaires, behavioral studies, and the use of physiological measures. Here, we compare the onsets of muscle activity using surface electromyography (EMG) while participants were walking under three different conditions: on a normal floor surface, on a narrow ribbon along the floor, and on a narrow platform raised off the floor. The same situation was rendered in an immersive virtual environment (IVE) Cave-like system, and 12 participants did the three types of walking in a counter-balanced within-groups design. The mean number of EMG activity onsets per unit time followed the same pattern in the virtual environment as in the physical environment-significantly higher for walking on the platform compared to walking on the floor. Even though participants knew that they were in fact really walking at floor level in the virtual environment condition, the visual illusion of walking on a raised platform was sufficient to influence their behavior in a measurable way. This opens up the door for this technique to be used in gait and posture related scenarios including rehabilitation.     

The physiological mirror—a system for unconscious control of a virtual environment through physiological activity

This paper introduces a system for real-time physiological measurement, analysis, and metaphorical visualization within a virtual environment (VE). Our goal is to develop a method that allows humans to unconsciously relate to parts of an environment more strongly than to others, purely induced by their own physiological responses to the virtual reality (VR) displays. In particular, we exploit heart rate, respiration, and galvanic skin response in order to control the behavior of virtual characters in the VE. Such unconscious processes may become a useful tool for storytelling or assist guiding participants through a sequence of tasks in order to make the application more interesting, e.g., in rehabilitation. We claim that anchoring of subjective bodily states to a virtual reality (VR) can enhance a person’s sense of realism of the VR and ultimately create a stronger relationship between humans and the VR.     

Piavca: a framework for heterogeneous interactions with virtual characters

This paper presents a virtual character animation system for real- time multimodal interaction in an immersive virtual reality setting. Human to human interaction is highly multimodal, involving features such as verbal language, tone of voice, facial expression, gestures and gaze. This multimodality means that, in order to simulate social interaction, our characters must be able to handle many different types of interaction and many different types of animation, simultaneously. Our system is based on a model of animation that represents different types of animations as instantiations of an abstract function representation. This makes it easy to combine different types of animation. It also encourages the creation of behavior out of basic building blocks, making it easy to create and configure new behaviors for novel situations. The model has been implemented in Piavca, an open source character animation system.     

Influence of oxygen content on some properties of Nb3Sn tape used for superconducting transmission lines

The influence of the presence of oxygen in the Nb-Zr substrate upon some physical and mechanical properties of the Nb-ZrO₂ substrate and/or Nb₃Sn tape superconductor prepared from such a substrate has been studied. The results have shown that the Nb₃Sn grains are much finer in the case of Nb-ZrO₂, than those obtained on Nb-Zr substrate. As a result, both the electrical and mechanical properties have been substantially improved. The critical current at a field of 5 T increased by between 100 and 200 %, the alternating current losses decreased by about one order of magnitude, the tensile strength increased by about a factor of three and the microhardness value also increased by about a factor of three for oxygen contents in the range 0.03 to 0.70 wt%. The specific resistance of this substrate increased at the same time from 17 to 22 cm and the relative elongation decreased from 5 to 3 %.     

Synthesis, structure, and physical properties of boron-doped diamond

Microcrystalline boron-doped diamond powders consisting of octahedrally faceted crystals have been synthesized in the C-H-B system at a pressure of 8 GPa and temperatures above 2000 K. The presence of boron has been shown to reduce the parameters of diamond synthesis compared to the binary system C-H (naphthalene). One possible reason for the reduction in synthesis parameters is the formation of less perfect graphite in the boron system in an intermediate step of diamond synthesis. At B/(C + B) ratios of about 5–10 at % in the C-H-B (naphthalene + boron) system, superconducting diamond microcrystals have been synthesized.     

Breakage of the induced mode synchronization in a solid state laser and the anomalous effect of spontaneous noise level on the synchronization bandwidth

The process of optical pulse formation in a solid state laser in the regime of induced mode synchronization and the development of breakage upon frequency detuning are considered based on a numerical solution of the Maxwell-Bloch equation. It is established that breakage of the sequence and shape of laser pulses in the course of an increase in the frequency detuning begins with the appearance of a periodic modulation of the pulse sequence envelope by low-frequency relaxation oscillations. These oscillations transform into regular spikes, which follow the scenario of period doubling that leads to a chaotic regime. It is also established that an optimum level of spontaneous noise exists at which the synchronization bandwidth is maximum, while the duration of pulses is minimum at a fixed loss modulation amplitude. This scheme of synchronization breakage was qualitatively confirmed in experiments on a YAG:Nd laser (λ = 1.06 μm) with cavity loss modulation at an intermode beat frequency.     

Inverted surface hysteresis loops in heterogeneous (nanocrystalline/amorphous) Fe<Subscript>81</Subscript>Nb<Subscript>7</Subscript>B<Subscript>12</Subscript> alloys

Inverted hysteresis loops were observed for the first time in the near-surface layers of heterogeneous (nanocrystalline/amorphous) Fe₈₁Nb₇B₁₂ alloys. In particular, a negative residual magnetization is retained when a positive magnetic field applied in the sample plane is decreased to zero. The inverted hysteresis is qualitatively explained within the framework of a two-phase model, according to which the heterogeneous alloys contain two dissimilar phases exhibiting uniaxial magnetic anisotropy and featuring antiferromagnetic exchange interaction.     

Problems of nondestructive testing of wheel-pair components of rolling stock

Improving the effectiveness of nondestructive testing of railway rolling stock’s wheel-pair components during their manufacturing and repair is considered. The results of metallographic studies of PY-1 and PY-1III solid-rolled wheels and axles, analysis of the operating specifications, and experimental studies of the optimal methods of nondestructive testing are included.     

Wear and life of tools with inserts from cBN-based polycrystalline Superhard materials in the finish turning of hardened steels at heavy feeds

The results have been considered of experimental studies of the wear regularities of tools with polycrystalline superhard materials based on cubic boron nitride (PCBN) in high-performance finishing of hardened steel with oblique cutters. The effect of machining conditions on the life of such tools has been analyzed.