Search

Many-core systems are susceptible to attacks launched by thermal covert channel (TCC) attacks. Detection of TCC attacks often relies on the use of threshold-based approaches or variants, and a countermeasure to thwart the channel can be applied only after an attack is deemed to be present. In this article, we describe a direct sequence spread spectrum (DSSS)-based TCC, where its thermal data are modulated by a pseudo-random bit sequence. Unfortunately, such DSSS-based TCC has an extremely low signal strength that the signal is nearly indistinguishable from the noise and thus cannot be detected by any existing threshold-based detection methods. To combat this stealthy TCC, we propose a novel detection scheme that lets the received signal pass through a differential filter where irrelevant frequency components occupied mainly by the noise gets eliminated and the filtered signal is next compared against a threshold for successful detection. Experimental results show that the DSSS-based TCC can effectively survive detection by the existing detection methods with its BER as low as 4%. In contrast, with the proposed detection and countermeasure applied, the detection accuracy jumps to 89%, and the BER of the DSSS-based TCC soars to 50%, which indicates that the TCC is practically shut down. [ABSTRACT FROM AUTHOR]

Legged robots are very promising for use in real-world applications, but their operation in narrow spaces is still challenging. One solution for enhancing their environmental adaptability is to design a small-sized biomimetic robot capable of performing multiple motions. By capturing a decent representation of an actual rat (rattus norvegicus), we developed a small-sized quadruped robotic rat (SQuRo), which includes four limbs and one flexible spine. On the basis of the extracted key movement joints, SQuRo was subtly designed with a relatively elongated slim body (aspect ratio: 3.42) and smaller weight (220 g) compared with quadruped robots of the same scale. Accordingly, we propose a control framework for multimodal motion planning, and the appropriate control parameters were tuned through optimization with consideration to the stability and actuation limits. The results obtained through a series of experimental tests reveal that SQuRo achieves a superior motion performance compared with existing state-of-the-art small-sized quadruped robots. Remarkably, SQuRo has an extremely small turning radius (0.48 BL) and strong payload capacity (200 g), and it can recover from falls. [ABSTRACT FROM AUTHOR]

This communication presents a novel single-layer, low-profile broadband metasurface (MTS)-inspired antenna with monopole-like radiation characteristics. To excite symmetric surface waves (SWs) propagating along an MTS consisting of an array of $4\times4$ metal square patches, a horizontal center-fed monopole structure is used at the center of the MTS. The proposed antenna is further embedded within a square ring to improve the gain and H-plane patterns roundness at the upper-frequency band. The presented antenna achieved a −10 dB bandwidth of 32.62% (5.08–7.06 GHz) and a low profile of $0.06\lambda _{0}$ ($\lambda _{0}$ is the free space wavelength at the center of the operating band) distinctive features due, respectively, to the effective excitation of different TM SW resonant modes that are close to each other and the in-phase reflection property of the MTS. The planar structure, single-layer, and low-profile merits make the proposed antenna an ideal candidate for various wireless communications systems, such as wireless local area network (WLAN) at 5.2/5.8 GHz, WiMAX at 5.5 GHz, and car to car (C2C) at 5.85–5.925 GHz. [ABSTRACT FROM AUTHOR]

This letter presents a differential ultralow power low-noise amplifier (LNA) with stacked three-stage common-source (CS) amplification cells. A three-coil transformer is developed to boost each stage’s $g_{m}$ and reuse current, which renders high gain, low noise, and low power consumption. The proposed LNA has been implemented in a 28-nm CMOS process and achieves a peak gain of 13.48 dB and a minimum noise figure (NF $_{\mathrm {min}}$) of 4.56 dB. The measured 3-dB gain bandwidth (${\text {BW}}_{3\,\text {dB}}$) is from 69.6 to 76.2 GHz. The LNA consumes 3.64-mW power from a 1.4-V supply and occupies 0.088-mm2 area excluding pads. [ABSTRACT FROM AUTHOR]

This article presents an ultralow power K-band frequency doubler operating under 0.4-V supply voltage. With 0-dBm input signal, the frequency doubler consumes 2.4 mW and achieves −8.4-dB conversion gain (CG). The measured saturated output power is −6 dBm at 23.6 GHz, and the 3-dB bandwidth is from 20.4 to 25.4 GHz. It exhibits up to 39-dB fundamental rejection (FR). The proposed differential frequency doubler operates at an ultralow supply voltage with ultralow power consumption in active frequency doublers. [ABSTRACT FROM AUTHOR]

To improve the performance of 3D LiDAR imaging and reduce the negative effects of interference fringes on polarization modulation of electro-optical crystals, a calibration algorithm based on polarization modulation principle was proposed in this letter. The reflect light of targets is received by the system, modulated by an electro-optical crystal, then divided into two complementary light beams after passing through polarization beam splitting (PBS), and finally received by two electron-multiplying CCDs (EMCCDs). The depth map and intensity image can be reconstructed by adding the two modulated images. However, the cone interference effect of the electro-optic crystal affects the modulation of the polarized light, resulting in the distance error. By fitting the curve of grayscale ratio of each pixel acquired by two EMCCDs with the changing of voltage, the actual range can be calculated by the light intensity corresponding to the accurate polarization modulation. Ultimately, we found that the algorithm showed outstanding performance on high-precision imaging with an error less than 0.1m in a wide field-of-view of 0.9 mrad. [ABSTRACT FROM AUTHOR]