Introducing olfactory display in the virtual reality (VR) system brings the immersive experience to new heights. However, it is intractable to simulate olfactory features (such as the intensity and the direction) with multiple levels. Visual stimuli have been proved to dominate human perception among multiple sensors in virtual environments. If visual stimuli can be used to guide the olfactory sense in VR, the design of the olfactory display can be simpler but still able to provide olfactory experience with more diversity. To understand the visual-olfactory effect on different olfactory characteristics, a portable olfactory display that can control the intensity and direction of odors was developed. An experimental study was conducted to investigate cross-modal human perception, i.e. how the visually virtual odor representation in VR influences human perception of real odor produced by the proposed olfactory display. The results showed that the perception of odor intensity and directionality can be modulated by visually virtual odor representation.

This paper proposes a 3rd-order low-distortion delta-sigma modulator (DSM) structure, which uses the timing-sharing technique between the 2nd and 3rd integrators during one clock phase. Further, since the operation phase of the 1st integrator is different to those of the 2nd and 3rd integrators, the three integrators are realized in just single opamp by the opamp sharing. Therefore, the power consumption can be reduced greatly. Besides, the proposed DSM structure poses the feature of relaxed feedback timing. The quantization and DEM operation can be extended from a non-overlapping interval for a conventional low-distortion structure to half of the clock period. The proposed 3rd-order 4-bit DSM is implemented in a 90-nm CMOS process. Post-layout simulation shows that the modulator achieves 75.1-dB SNDR with 2.5-MHz input signal bandwidth and 80-MHz sampling frequency. The power consumption is only 1.42 mW with 61.1-fJ/conversion-step FOM, and the core area is 683 × 592 μm2.

In this paper, we present a double-ring mobile-to-mobile channel model based upon a three-dimensional (3D) space-time-frequency correlation function via combining the antenna pattern, Doppler shift, and delay profile. This 3-D correlation function results in the probability density distribution (PDF) of an extra elevation angle (EA) being taken into the antenna pattern and the Doppler shift consideration. Four types of the EA PDF, Aulin, Parsons, Qu-Yeap, and uniform models, have been discussed. It is revealed through computer simulations that the 3-D scattering scenario outperforms the two-dimensional environment in terms of the cross-correlation for all four types of the EA PDFs. Furthermore, we find that the performance of the uniform model is better than the others when the radius of the circular antenna array is more than 0.5 times of the propagation wavelength, or 7.5 cm for a 2 GHz carrier frequency.