| 71. |
- Chen, Qinyu, et al.
(författare)
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An Efficient Accelerator for Multiple Convolutions From the Sparsity Perspective
- 2020
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Ingår i: IEEE Transactions on Very Large Scale Integration (vlsi) Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1063-8210 .- 1557-9999. ; 28:6, s. 1540-1544
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Tidskriftsartikel (refereegranskat)abstract
- Convolutional neural networks (CNNs) have emerged as one of the most popular ways applied in many fields. These networks deliver better performance when going deeper and larger. However, the complicated computation and huge storage impede hardware implementation. To address the problem, quantized networks are proposed. Besides, various convolutional structures are designed to meet the requirements of different applications. For example, compared with the traditional convolutions (CONVs) for image classification, CONVs for image generation are usually composed of traditional CONVs, dilated CONVs, and transposed CONVs, leading to a difficult hardware mapping problem. In this brief, we translate the difficult mapping problem into the sparsity problem and propose an efficient hardware architecture for sparse binary and ternary CNNs by exploiting the sparsity and low bit-width characteristics. To this end, we propose an ineffectual data removing (IDR) mechanism to remove both the regular and irregular sparsity based on dual-channel processing elements (PEs). Besides, a flexible layered load balance (LLB) mechanism is introduced to alleviate the load imbalance. The accelerator is implemented with 65-nm technology with a core size of 2.56 mm(2). It can achieve 3.72-TOPS/W energy efficiency at 50.1 mW, which makes it a promising design for embedded devices.
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| 72. |
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| 73. |
- Chen, Qiao, et al.
(författare)
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Dual-polarized Geodesic Lens Antenna at sub-THz
- 2023
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Ingår i: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP. - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- We present a dual-polarized lens antenna for point-to-multipoint communications at sub-THz. The lens is constructed by a doubly-curved parallel plate following a geodesic lens shape equivalent to the Luneburg index profile. The polarization is changed by metallic screens patterned with complementary split resonant rings (CSRRs). These screens are integrated in the radiation aperture of the lens. Two lenses are stacked up, one for each polarization. Each lens is fed by 11 waveguide ports, providing beam steering or multiple beams. The antenna is fully metallic and hence, highly efficient. In the operating band from 115 GHz to 125 GHz, the simulation shows a realized gain of 20 dBi with a maximum scan loss of 0.6 dB up to 60 degrees, a cross-polarization discrimination around 20 dB, and an insertion loss smaller than 1.5 dB.
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| 74. |
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| 75. |
- Chen, Shouzhi, et al.
(författare)
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Influences of Shifted Vegetation Phenology on Runoff Across a Hydroclimatic Gradient
- 2022
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Climate warming has changed vegetation phenology, and the phenology-associated impacts on terrestrial water fluxes remain largely unquantified. The impacts are linked to plant adjustments and responses to climate change and can be different in different hydroclimatic regions. Based on remote sensing data and observed river runoff of hydrological station from six river basins across a hydroclimatic gradient from northeast to southwest in China, the relative contributions of the vegetation (including spring and autumn phenology, growing season length (GSL), and gross primary productivity) and climatic factors affecting the river runoffs over 1982–2015 were investigated by applying gray relational analysis (GRA). We found that the average GSLs in humid regions (190–241 days) were longer than that in semi-humid regions (186–192 days), and the average GSLs were consistently extended by 4.8–13.9 days in 1982–2015 period in six river basins. The extensions were mainly linked to the delayed autumn phenology in the humid regions and to advanced spring phenology in the semi-humid regions. Across all river basins, the GRA results showed that precipitation (r = 0.74) and soil moisture (r = 0.73) determine the river runoffs, and the vegetation factors (VFs) especially the vegetation phenology also affected the river runoffs (spring phenology: r = 0.66; GSL: r = 0.61; autumn phenology: r = 0.59), even larger than the contribution from temperature (r = 0.57), but its relative importance is climatic region-dependent. Interestingly, the spring phenology is the main VF in the humid region for runoffs reduction, while both spring and autumn growth phenology are the main VFs in the semi-humid region, because large autumn phenology delay and less water supply capacity in spring amplify the effect of advanced spring phenology. This article reveals diverse linkages between climatic and VFs, and runoff in different hydroclimatic regions, and provides insights that vegetation phenology influences the ecohydrology process largely depending on the local hydroclimatic conditions, which improve our understanding of terrestrial hydrological responses to climate change.
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| 76. |
- Chen, Shouzhi, et al.
(författare)
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Informing the SWAT model with remote sensing detected vegetation phenology for improved modeling of ecohydrological processes
- 2023
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694. ; 616
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Tidskriftsartikel (refereegranskat)abstract
- The Soil and Water Assessment Tool (SWAT) model has been widely applied for simulating the water cycle and quantifying the influence of climate change and anthropogenic activities on hydrological processes. A major uncertainty of SWAT stems from the poor representation of vegetation dynamics due to the use of a simplistic vegetation growth and development module. Using long-term remote sensing-based phenological data, the SWAT model's vegetation module was improved by adding a dynamic growth start date and the dynamic heat requirement for vegetation growth rather than using constant values. The new SWAT model was verified in the Han River basin, China, and found its performance was much improved in comparison with that of the original SWAT model. Specifically, the accuracy of the leaf area index (LAI) simulation improved notably (coefficient of determination (R2) increased by 0.193, Nash–Sutcliffe Efficiency (NSE) increased by 0.846, and percent bias decreased by 42.18 %), and that of runoff simulation improved modestly (R2 increased by 0.05 and NSE was similar). Additionally, it is found that the original SWAT model substantially underestimated evapotranspiration (Penman-Monteith method) in comparison with the new SWAT model (65.09 mm (or 22.17 %) for forests, 92.27 mm (or 32 %) for orchards, and 96.16 mm (or 36.4 %) for farmland), primarily due to the inaccurate representation of LAI dynamics. Our results suggest that an accurate representation of phenological dates in the vegetation growth module is important for improving the SWAT model performance in terms of estimating terrestrial water and energy balance.
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| 77. |
- Chen, Shiqian, et al.
(författare)
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Ultrafast metal-free microsupercapacitor arrays directly store instantaneous high-voltage electricity from mechanical energy harvesters
- 2024
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Ingår i: Advanced Science. - : Wiley. - 2198-3844. ; 11:22
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Tidskriftsartikel (refereegranskat)abstract
- Harvesting renewable mechanical energy is envisioned as a promising and sustainable way for power generation. Many recent mechanical energy harvesters are able to produce instantaneous (pulsed) electricity with a high peak voltage of over 100 V. However, directly storing such irregular high-voltage pulse electricity remains a great challenge. The use of extra power management components can boost storage efficiency but increase system complexity. Here utilizing the conducting polymer PEDOT:PSS, high-rate metal-free micro-supercapacitor (MSC) arrays are successfully fabricated for direct high-efficiency storage of high-voltage pulse electricity. Within an area of 2.4 × 3.4 cm2 on various paper substrates, large-scale MSC arrays (comprising up to 100 cells) can be printed to deliver a working voltage window of 160 V at an ultrahigh scan rate up to 30 V s−1. The ultrahigh rate capability enables the MSC arrays to quickly capture and efficiently store the high-voltage (≈150 V) pulse electricity produced by a droplet-based electricity generator at a high efficiency of 62%, significantly higher than that (<2%) of the batteries or capacitors demonstrated in the literature. Moreover, the compact and metal-free features make these MSC arrays excellent candidates for sustainable high-performance energy storage in self-charging power systems.
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| 78. |
- Chen, Shouzhi, et al.
(författare)
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Vegetation phenology and its ecohydrological implications from individual to global scales
- 2022
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Ingår i: Geography and Sustainability. - : Elsevier BV. - 2096-7438 .- 2666-6839. ; 3:4, s. 334-338
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Tidskriftsartikel (refereegranskat)abstract
- The Earth is experiencing unprecedented climate change. Vegetation phenology has already showed strong response to the global warming, which alters mass and energy fluxes on terrestrial ecosystems. With technology and method developments in remote sensing, computer science and citizen science, many recent phenology-related studies have been focused on macrophenology. In this perspective, we 1) reviewed the responses of vegetation phenology to climate change and its impacts on carbon cycling, and reported that the effect of shifted phenology on the terrestrial carbon fluxes is substantially different between spring and autumn; 2) elaborated how vegetation phenology affects ecohydrological processes at different scales, and further listed the key issues for each scale, i.e., focusing on seasonal effect, local feedbacks and regional vapor transport for individual, watershed and global respectively); 3) envisioned the potentials to improve current hydrological models by coupling vegetation phenology-related processes, in combining with machine learning, deep learning and scale transformation methods. We propose that comprehensive understanding of climate-macrophenology-hydrology interactions are essential and urgently needed for enhancing our understanding of the ecosystem response and its role in hydrological cycle under future climate change.
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| 79. |
- Chen, Xiaojing, et al.
(författare)
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Guideline-directed medical therapy in real-world heart failure patients with low blood pressure and renal dysfunction
- 2021
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Ingår i: Clinical Research in Cardiology. - : SPRINGER HEIDELBERG. - 1861-0684 .- 1861-0692. ; 110, s. 1051-1062
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Tidskriftsartikel (refereegranskat)abstract
- Background Among patients with heart failure and reduced ejection fraction (HFrEF), angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers (ACEI/ARB), beta-blockers (BB) and mineralocorticoid receptor antagonist (MRA) are known as guideline-directed medical therapy to improve prognosis. However, low blood pressure (BP) and renal dysfunction are often challenges prevent clinical implementation, so we investigated the association of different combinations of GDMT treatments with all-cause mortality in HFrEF population with low BP and renal dysfunction. Methods This study initially included 51, 060 HF patients from the Swedish Heart Failure Registry, and finally 1464 HFrEF patients with low BP (systolic BP <= 100 mmHg) and renal dysfunction (estimated glomerular filtration rate (eGFR) <= 60 ml/min/1.73m(2)) were ultimately enrolled. Patients were receiving oral medication for HF at study enrollment, and divided into four groups (group 1-4: ACEI/ARB + BB + MRA, ACEI/ARB + BB, ACEI/ARB + MRA or ACEI/ARB only, and other). The outcome is time to all-cause mortality. Results Among the study patients, 485 (33.1%), 672 (45.9%), 109 (7.4%) and 198 (13.5%) patients were in group 1-4. Patients in group 1 were younger, had highest hemoglobin, and most with EF < 30%. During a median of 1.33 years follow-up, 937 (64%) patients died. After adjustment for age, gender, LVEF, eGFR, hemoglobin when compared with the group 1, the hazard ratio for all-cause mortality in group 2 was 1.04 (0.89-1.21) (p = 0.62), group 3 1.40 (1.09-1.79) (p = 0.009), and group 4 1.71 (1.39-2.09) (p < 0.001). Conclusions In real-world HFrEF patients with low BP and renal dysfunction, full medication of guideline-directed medical therapy is associated with improved survival. The benefit was larger close to the index date and decreased with follow-up time.
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| 80. |
- Chen, Xiaojing, et al.
(författare)
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High-normal blood pressure conferred higher risk of cardiovascular disease in a random population sample of 50-year-old men: A 21-year follow-up.
- 2020
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Ingår i: Medicine. - 1536-5964. ; 99:17
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Tidskriftsartikel (refereegranskat)abstract
- The relationship between various categories of blood pressure (BP), subtypes of hypertension, and development of cardiovascular disease (CVD) have not been extensively studied. Therefore, our study aimed to explore this relationship in a random population sample of men born in 1943, living in Sweden and followed over a 21-year period.Participants were examined for the first time in 1993 (age 50 years), where data on medical history, concomitant diseases, and general health were collected. The examination was repeated in 2003 and with additional echocardiography also in 2014. Classification of participants according to their BP at the age of 50 years was as follows: optimal-normal BP (systolic blood pressure [SBP] <130 and diastolic BP [DBP] <85mmHg), high-normal BP (130≤SBP<140, 85≤DBP<90mmHg), isolated systolic-diastolic hypertension (ISH-IDH) (SBP ≥140 and DBP <90 or SBP <140 and DBP ≥90mmHg), and systolic-diastolic hypertension (SDH) (SBP ≥140 and DBP ≥90mmHg).During the follow-up, the incidence of heart failure (HF), CVD, and coronary heart disease were all lowest for those with optimal-normal BP. Participants with high-normal BP showed greater wall thickness and left ventricular mass index, larger LV size and larger left atrial size when compared with the optimal-normal BP group. Furthermore, those with high-normal BP, ISH-IDH, and SDH had a higher risk of CVD than those with optimal-normal BP. The adjusted relative risk of CVD was highest for SDH (hazard ratio [HR] 1.95; 95% confidence interval [95% CI] 1.37-2.79), followed by ISH-IDH (HR 1.34; 95% CI 0.93-1.95) and high-normal BP (HR 1.31; 95% CI 0.91-1.89).Over a 21-year follow-up, the participants with high-normal BP or ISH-IDH had a higher relative risk of CVD than those with optimal-normal BP.
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