Autocalibration with the Minimum Number of Cameras with Known Pixel Shape

In 3D reconstruction, the recovery of the calibration parameters of the cameras is paramount since it provides metric information about the observed scene, e.g., measures of angles and ratios of distances. Autocalibration enables the estimation of the camera parameters without using a calibration device, but by enforcing simple constraints on the camera parameters. In the absence of information about the internal camera parameters such as the focal length and the principal point, the knowledge of the camera pixel shape is usually the only available constraint. Given a projective reconstruction of a rigid scene, we address the problem of the autocalibration of a minimal set of cameras with known pixel shape and otherwise arbitrarily varying intrinsic and extrinsic parameters. We propose an algorithm that only requires 5 cameras (the theoretical minimum), thus halving the number of cameras required by previous algorithms based on the same constraint. To this purpose, we introduce as our basic geometric tool the six-line conic variety (SLCV), consisting in the set of planes intersecting six given lines of 3D space in points of a conic. We show that the set of solutions of the Euclidean upgrading problem for three cameras with known pixel shape can be parameterized in a computationally efficient way. This parameterization is then used to solve autocalibration from five or more cameras, reducing the three-dimensional search space to a two-dimensional one. We provide experiments with real images showing the good performance of the technique.Comment: 19 pages, 14 figures, 7 tables, J. Math. Imaging Vi

Addressing climate change with behavioral science:A global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions' effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior-several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people's initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors.</p

Addressing climate change with behavioral science: a global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions’ effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior—several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people’s initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors

Addressing climate change with behavioral science:A global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions' effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior-several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people's initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors.</p

A WCDMA/WLAN digital polar transmitter with AM replica feedback linearization in 65nm CMOS

A 65nm CMOS digital polar transmitter for WCDMA and WLAN is presented, which consists of a 9bit digitally-controlled switch-capacitor polar modulator and a 6-bit power amplifier array with a proposed linearity-enhancement technique. Even without AM-AM pre-distortion, the transmitter system measures RMS-EVM of 2.83% and 4.07% for WCDMA and WLAN 54-Mb/s OFDM, respectively; while providing a peak output power of 20.4dBm with PAE 32.3% © 2012 IEEE

A 36/44 MHz switched-capacitor bandpass filter for cable-TV tuner application

A 36/44-MHz wide-band switched-capacitor (SC) band-pass filter is proposed for cable-TV tuner systems. The 14^th-order SC biquadratic filter employs 2-path technique to achieve high attenuation and wide bandwidth at high frequency. Implemented in a 0.18-μm CMOS process, the filter measures center frequencies of 36 MHz and 44 MHz with a bandwidth of 5.0 MHz and 6.2 MHz, respectively. Adjacent-channel attenuation of-58 dBc and pass-band ripple of less than 0.6 dB are achieved. ©2006 IEEE

A 0.9-V double-balanced quadrature-input quadrature-output frequency divider

A double-balanced quadrature-input quadrature-output (QIQO) divider is proposed. By making use of the quadrature phase outputs from a quadrature VCO (QVCO) or the other quadrature signal generator, the proposed QIQO divider provides a mechanism to achieve an output IQ phase sequence that is inherently tracked with the input IQ phase sequence. Moreover, compared with conventional dividers, the QIQO divider not only provides smaller and better-matched input loading to the QVCO but also improved quadrature phase accuracy for both QVCO and the divider itself. Fabricated in a 0.18-μm CMOS process and operated at 0.9 V, the QIQO divider measures an image rejection of-62 dBc while consuming 7.2 mW. © 2006 IEEE

Transformer-based current-gain-boost technique for dual-band and wide-band receiver front-ends

Dual-band and wide-band receiver-front-ends (RFEs) using transformer-based current-gain-boost techniques are designed in 0.13μm CMOS. With a single switchable 3-coil transformer, the first dual-band RFE prototype measures NF of 2.5dB and 3.5dB and voltage gain of 20.7dB and 17dB at 1.7GHz and 3.8GHz, respectively. The second wide-band RFE achieves 0dBm IIP3 with 4dB NF and 13dB voltage gain over a frequency range from 2GHz to 5GHz. © 2012 IEEE

A 1V 1.7mW 25GHz transformer-feedback divide-by-3 frequency divider with quadrature outputs

A transformer-feedback injection-locked divide-by-3 frequency divider (ILFD) is proposed. Employing a transformer feedback, the divider can achieve high performance in terms of low voltage, high frequency, and low power consumption. Fabricated in a 0.13-μm CMOS process and operated at a 1-V supply voltage, the divider prototype measures an input frequency range from 22.7GHz to 25.1GHz with 2^nd and 3rd harmonic tones of -45 dBc and -40 dBc respectively. With quadrature outputs, the divider achieves a sideband rejection ratio of 40 dB while consuming 1.7mW and occupying an active area of 0.23mm². © 2007 IEEE