| 751. |
- Qin, Zidi, et al.
(författare)
-
A Novel Approximation Methodology and Its Efficient VLSI Implementation for the Sigmoid Function
- 2020
-
Ingår i: IEEE Transactions on Circuits and Systems - II - Express Briefs. - : Institute of Electrical and Electronics Engineers (IEEE). - 1549-7747 .- 1558-3791. ; 67:12, s. 3422-3426
-
Tidskriftsartikel (refereegranskat)abstract
- In this brief, a novel approximation method and its optimized hardware implementation are proposed for the sigmoid function used in Deep Neural Networks (DNNs). Based on piecewise approximation and truncated Taylor series expansion, the proposed method achieves very good approximation with low complexity while exploiting data representation with powers of two. In addition, by analyzing gradients of the sigmoid function, a small trick is introduced to improve the approximation precision. Furthermore, to reduce the hardware complexity and shorten the critical path, sampled values of the function are generated with simple logical-mapping. It is shown that the proposed approximation schemes can be implemented with purely combinational logic and the sigmoid function can be computed in one clock cycle. The experimental results demonstrate that the mean absolute errors are at the order of 1 x 10(-3). Compared with prior arts, the new design can obtain significant improvement in critical path with comparable performance.
|
|
| 752. |
- Qin, Zidi, et al.
(författare)
-
A Universal Approximation Method and Optimized Hardware Architectures for Arithmetic Functions Based on Stochastic Computing
- 2020
-
Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 8, s. 46229-46241
-
Tidskriftsartikel (refereegranskat)abstract
- Stochastic computing (SC) has been applied on the implementations of complex arithmetic functions. Complicated polynomial-based approximations lead to large hardware complexity of previous SC circuits for arithmetic functions. In this paper, a novel piecewise approximation method based on Taylor series expansion is proposed for complex arithmetic functions. Efficient implementations based on unipolar stochastic logic are presented for the monotonic functions. Furthermore, detailed optimization schemes are provided for the non-monotonic functions. Using NAND and AND gates as main computing elements, the optimized hardware architectures have extremely low complexity. The experimental results show that a broad range of arithmetic functions can be implemented with the proposed SC circuits, and the mean absolute errors can achieve the order of 1 x 10(-3). Compared with the state-of-the-art works, the approximation precision for some typical functions can be increased by more than 8x with our method. In addition, the proposed circuits outperform the previous methods in hardware complexity and critical path significantly.
|
|
| 753. |
- Qin, Zijun, et al.
(författare)
-
Reinforcement-Learning-Based Overhead Reduction for Online Fountain Codes With Limited Feedback
- 2023
-
Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778 .- 1558-0857. ; 71:7, s. 3977-3991
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the application of reinforcement learning (RL) on online fountain codes, and propose two schemes to reduce the full-recovery overhead with limited feedback. First, we use RL in determining the optimal degree of coded symbols for a given number of feedback, and propose the RL-based degree determination (RL-DD), with the help of theoretical analysis of the relationship between recovery rate and buffer occupancy. Then we propose online fountain codes with no build-up phase using sectioned distribution (OFCNB-SD), where the encoder sends symbols whose degrees are sampled from different sections of an overall distribution, and the decoder is improved to utilize coded symbols that are not immediately decodable. We present theoretical analysis of OFCNB-SD, and introduce RL-based sectioned distribution (RL-SD) scheme where the sectioning of the overall distribution is optimized with RL. Simulation results show that our proposed schemes could achieve lower full-recovery overhead with limited feedback compared to existing schemes.
|
|
| 754. |
- Qin, Zhilian, et al.
(författare)
-
Vertical distributions of organic carbon fractions under paddy and forest soils derived from black shales : Implications for potential of long-term carbon storage
- 2021
-
Ingår i: Catena (Cremlingen. Print). - : Elsevier. - 0341-8162 .- 1872-6887. ; 198, s. 1-8
-
Tidskriftsartikel (refereegranskat)abstract
- Black shales are characterized by a high content of organic carbon (C). Few studies have focused on the influence of land use on soil organic C (SOC) fractions from soils derived from black shale (black shale soils). The objective of this study was to elucidate the influence of land use on SOC fractions in black shale soils combining chemical determination and stable C isotope analysis techniques. Herein, we determined labile organic C (LOC), semilabile organic C (Semi-LOC), and recalcitrant organic C (ROC) fractions in various depths of soils in paddy fields (0-70 cm) and forests (0-120 cm) from black shale distribution region in Hunan province, China, and then investigated delta C-13 values of these soils. Results showed that the contents of LOC, Semi-LOC, and ROC in paddy soils (1.63-7.35 g kg(-1), 0.35-1.21 g kg(-1), and 3.75-14.8 g kg(-1), respectively) and forest soils (0.73-4.94 g kg(-1), 0.12-0.89 g kg(-1), and 1.44-8.96 g kg(-1), respectively) are significantly decreased with increasing depth. The contribution made by LOC to SOC in paddy soils was significantly lower than that in forest soils, while the contribution made by ROC to SOC was significantly higher in paddy soils than that in forest soils. In these two land uses, the delta C-13 values were higher in SOC compared to the ROC fraction, while the delta C-13 values were close in the ROC fraction below 20 cm soil depth. Our study indicated that i) new C is mainly limited to the surface soil layer (0-10 cm) in forests, while it can be leached along the soil profiles in paddy fields; ii) the estimated ROC pool is similar to 900 Pg within the 0-100 cm soil layer in terrestrial ecosystems, which should better represent the ability of soil C sequestration.
|
|
| 755. |
- Qinlu, Lin, et al.
(författare)
-
Influence of amphiphilic structures on the stability of polyphenols with different hydrophobicity
- 2007
-
Ingår i: Science in China. Series B: Chemistry. - : Springer Science and Business Media LLC. - 1006-9291 .- 1862-2771. ; 50:1, s. 121-126
-
Tidskriftsartikel (refereegranskat)abstract
- Autooxidation of five polyphenols representing range of different hydrophobicities (catechin gallate (CG), (-) catechin((-)C), epicatechin (EC), epigallocatechin gallate (EGCG) and epigallocatechin (EGC)) in three different aqueous solutions: molecular solution, micellar solution (Tween-20) and liposomal dispersion (soybean lecithin) was monitored by HPLC. The rate of oxidation of the five polyphenols was higher at pH 4.5 than at pH 3.5. Compared with the control, addition of Tween-20 (micellar structure) and lecithin (liposomal structure) significantly decreased the degradation of polyphenols. In the presence of lecithin the autooxidation of all the five polyphenols was slower than in the presence of Tween-20. The effective protection of the colloidal structures was compared with the hydrophobicity of the polyphenols estimated from the partitioning between octanol and water. The protection from oxidation in the presence of the colloidal structures (micellar or liposomal) increased with increasing partitioning of a polyphenol towards the hydrophobic environment. The protecting effect of the colloidal structures was more effective at pH 4.5 than at pH 3.5.
|
|
| 756. |
|
|
| 757. |
- Quintana, Crisanto, et al.
(författare)
-
A high speed retroreflective free space optics links with UAV
- 2021
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 39:18, s. 5699-5705
-
Tidskriftsartikel (refereegranskat)abstract
- In this work we report the design and implementation of a very high speed retroreflective free space communication system between a ground station and a commercial unmanned aerial vehicle (UAV). The system uses a pixelated electro-absorption modulator (EAM) modulating retroreflector (MRR) to establish a data link operating at 500 Mbps at a range of 560 m and a bit error rate (BER) of 7.610-4. The MRR provides an effective aperture of 11mm and full field of view (FFOV) of 6.4. To the best of our knowledge, this is the fastest demonstration of an outdoor link of this type. In this paper the design and implementation of the system is described, as well as results from experimental trials.
|
|
| 758. |
- Radamson, Henry H., et al.
(författare)
-
Optimization of Selective Growth of SiGe for Source/Drain in 14nm and beyond Nodes FinFETs
- 2017
-
Ingår i: International Journal of High Speed Electronics and Systems. - : World Scientific Publishing Co. Pte Ltd. - 0129-1564. ; 26:1-2
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, optimization of selective epitaxy growth (SEG) of SiGe layers on source/drain (S/D) areas in 14nm node FinFETs with high-k & metal gate has been presented. The Ge content in epilayers was in range of 30%-40% with boron concentration of 1-3 × 1020 cm-3. The strain distribution in the transistor structure due to SiGe as stressor material in S/D was simulated and these results were used as feedback to design the layer profile. The epitaxy parameters were optimized to improve the layer quality and strain amount of SiGe layers. The in-situ cleaning of Si fins was crucial to grow high quality layers and a series of experiments were performed in range of 760-825 °C. The results demonstrated that the thermal budget has to be within 780-800 °C in order to remove the native oxide but also to avoid any harm to the shape of Si fins. The Ge content in SiGe layers was directly determined from the misfit parameters obtained from reciprocal space mappings using synchrotron radiation. Atomic layer deposition (ALD) technique was used to deposit HfO2 as high-k dielectric and B-doped W layer as metal gate to fill the gate trench. This type of ALD metal gate has decent growth rate, low resistivity and excellent capability to fill the gate trench with high aspect-ratio. Finally, the electrical characteristics of fabricated FinFETs were demonstrated and discussed.
|
|
| 759. |
- Radamson, Henry H., et al.
(författare)
-
Optimization of Selective Growth of SiGe for Source/Drain in 14nm and Beyond Nodes FinFETs
- 2017
-
Ingår i: Scaling and Integration of High-Speed Electronics and Optomechanical Systems. - : World Scientific Pub Co Pte Ltd. ; , s. 99-107
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In this work, optimization of selective epitaxy growth (SEG) of SiGe layers on source/drain (S/D) areas in 14nm node FinFETs with high-k and metal gate has been presented. The Ge content in epilayers was in range of 30%-40% with boron concentration of 1-3 × 1020 cm-3. The strain distribution in the transistor structure due to SiGe as stressor material in S/D was simulated and these results were used as feedback to design the layer profile. The epitaxy parameters were optimized to improve the layer quality and strain amount of SiGe layers. The in-situ cleaning of Si fins was crucial to grow high quality layers and a series of experiments were performed in range of 760-825 °C. The results demonstrated that the thermal budget has to be within 780-800 °C in order to remove the native oxide but also to avoid any harm to the shape of Si fins. The Ge content in SiGe layers was directly determined from the misfit parameters obtained from reciprocal space mappings using synchrotron radiation. Atomic layer deposition (ALD) technique was used to deposit HfO2 as high-k dielectric and B-doped W layer as metal gate to fill the gate trench. This type of ALD metal gate has decent growth rate, low resistivity and excellent capability to fill the gate trench with high aspect-ratio. Finally, the electrical characteristics of fabricated FinFETs were demonstrated and discussed.
|
|
| 760. |
- Ren, Weixi, et al.
(författare)
-
An intelligent optimization method for the facility environment on rural roads
- 2024
-
Ingår i: Computer-Aided Civil and Infrastructure Engineering. - 1093-9687 .- 1467-8667. ; In Press
-
Tidskriftsartikel (refereegranskat)abstract
- This study develops an intelligent optimization method of the facility environment (i.e., road facilities and surrounding landscapes) from drivers’ visual perception to adjust operation speeds on rural roads. Different from previous methods that heavily rely on expert experience and are time-consuming, this method can rapidly generate optimized visual images of the facility environment and promptly verify the optimization effects. In this study, a visual road schema model is established to quantify the facility environment from drivers’ visual perception, and an automated optimization scheme determination approach considering the original facility environment characteristics is proposed using self-explaining theory. Then, Cycle-consistent generative adversarial network is used to automatically generate optimized facility environment images. To verify the optimization effect, operation speeds of the optimized facility environments are predicted using random forest. The case study shows that this method can effectively optimize the facility environment where original operation speeds are more than 20% over the speed limits, and the whole process only takes 1 h far less than several months or years in previous ways. Overall, this study advances the intelligence level in optimizing the facility environment and enhances rural road safety.
|
|
