16 results on '"Shiyang Hu"'
Search Results
2. Service evaluation and promotion strategies for different types of parks in Shenzhen
- Author
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Juan Liu, Yiyong Chen, Hao Yin, Dimei Ouyang, Shiyang Hu, and Kexin Cao
- Subjects
Service (business) ,Promotion (rank) ,media_common.quotation_subject ,Computer Science (miscellaneous) ,Business ,Marketing ,Engineering (miscellaneous) ,media_common - Published
- 2021
3. Automatic multi‐organ segmentation in dual‐energy CT (DECT) with dedicated 3D fully convolutional DECT networks
- Author
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Shuqing Chen, Andreas Maier, Sabrina Dorn, Shiyang Hu, Marc Kachelrieß, Xia Zhong, and Michael Lell
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Thorax ,Computer science ,Spleen ,Computed tomography ,Signal-To-Noise Ratio ,Kidney ,Convolutional neural network ,030218 nuclear medicine & medical imaging ,Radiography, Dual-Energy Scanned Projection ,03 medical and health sciences ,Deep Learning ,0302 clinical medicine ,Abdomen ,Image Processing, Computer-Assisted ,medicine ,Humans ,Segmentation ,Lung ,medicine.diagnostic_test ,business.industry ,Deep learning ,Digital Enhanced Cordless Telecommunications ,Dose-Response Relationship, Radiation ,Pattern recognition ,General Medicine ,Models, Theoretical ,Multi organ ,medicine.anatomical_structure ,Liver ,030220 oncology & carcinogenesis ,ddc:000 ,Dual energy ct ,Artificial intelligence ,Tomography, X-Ray Computed ,business ,Energy (signal processing) - Abstract
Purpose Dual-energy computed tomography (DECT) has shown great potential in many clinical applications. By incorporating the information from two different energy spectra, DECT provides higher contrast and reveals more material differences of tissues compared to conventional single-energy CT (SECT). Recent research shows that automatic multi-organ segmentation of DECT data can improve DECT clinical applications. However, most segmentation methods are designed for SECT, while DECT has been significantly less pronounced in research. Therefore, a novel approach is required that is able to take full advantage of the extra information provided by DECT. Methods In the scope of this work, we proposed four three-dimensional (3D) fully convolutional neural network algorithms for the automatic segmentation of DECT data. We incorporated the extra energy information differently and embedded the fusion of information in each of the network architectures. Results Quantitative evaluation using 45 thorax/abdomen DECT datasets acquired with a clinical dual-source CT system was investigated. The segmentation of six thoracic and abdominal organs (left and right lungs, liver, spleen, and left and right kidneys) were evaluated using a fivefold cross-validation strategy. In all of the tests, we achieved the best average Dice coefficients of 98% for the right lung, 98% for the left lung, 96% for the liver, 92% for the spleen, 95% for the right kidney, 93% for the left kidney, respectively. The network architectures exploit dual-energy spectra and outperform deep learning for SECT. Conclusions The results of the cross-validation show that our methods are feasible and promising. Successful tests on special clinical cases reveal that our methods have high adaptability in the practical application.
- Published
- 2020
4. Model Predictive Control for Virtual Synchronous Generator with Improved Vector Selection and Reconstructed Current
- Author
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Yanyan Li, Nan Jin, Jie Fang, Shiyang Hu, and Chao Pan
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Control and Optimization ,model predictive control ,Computer science ,020209 energy ,Energy Engineering and Power Technology ,voltage vector ,02 engineering and technology ,lcsh:Technology ,Control theory ,Frequency grid ,0202 electrical engineering, electronic engineering, information engineering ,Power grid ,Electrical and Electronic Engineering ,Engineering (miscellaneous) ,current reconstruction ,lcsh:T ,Renewable Energy, Sustainability and the Environment ,business.industry ,020208 electrical & electronic engineering ,virtual synchronous generator ,Grid ,Renewable energy ,Power (physics) ,Model predictive control ,business ,Pulse-width modulation ,Energy (miscellaneous) ,Voltage - Abstract
Due to the large-scale renewable energy connected to the power grid by power electronic converters, the inertia and stability of the power grid is declining. In order to improve the inertia and support the grid recovery, the three-phase converter works as a virtual synchronous generator (VSG) to respond to the frequency and voltage changes of the power grid. This paper proposes a model predictive control for the virtual synchronous generator (MPC-VSG) strategy, which can automatically control the converter output power with the grid frequency and voltage changes. Further consideration of fault-tolerant ability and reliability, the method based on improved voltage vector selection, and reconstructed current is used for MPC-VSG to ensure continuous operation for three-phase converters that have current-sensor faults, and improve the reconstruction precision. The proposed method can respond to the frequency and voltage changes of the power grid and has fault-tolerant ability, which is easy to realize without pulse width modulation (PWM) and a proportional-integral (PI) controller. The effectiveness of the proposed control strategy is verified by experiment.
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- 2020
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5. Attention, Lottery, or Salience? The Impact of Extreme Payoffs on Chinese Mutual Fund Flows
- Author
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Cheng Xiang, Shiyang Hu, and Xiaofeng Quan
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Lottery ,Salience (language) ,Financial economics ,If and only if ,business.industry ,Salient ,Economics ,Sample (statistics) ,Asset (economics) ,Set (psychology) ,business ,Mutual fund - Abstract
Using a sample of Chinese mutual funds from 2004 to 2019, we find that investors direct flows into (out of) funds with salient upsides (downsides), controlling for a set of known determinants of fund flows. This effect is robust to alternative measures of key variables and is more pronounced for funds with larger individual ownership. This effect is not explained by individuals’ attention-driven purchases of attention-grabbing funds, funds’ lottery-like features, or the characteristics of funds’ underlying stocks. The salience theory, which argues that extreme payoffs distort individuals’ decision weights on risky asset choices only if these payoffs stand out relative to available alternatives and thus are salient, offers a plausible explanation for this effect.
- Published
- 2020
6. On the Characteristics of Helical 3D X-Ray Dark-Field Imaging
- Author
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Lina Felsner, Andreas Maier, Gisela Anton, Shiyang Hu, Veronika Ludwig, and Christian Riess
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Physics ,Optics ,Scattering ,business.industry ,Fiber (mathematics) ,Orientation (computer vision) ,Trajectory ,Physics::Optics ,Point (geometry) ,Grating ,business ,Linear combination ,Signal - Abstract
The X-ray dark-field can be measured with a grating interferometer. For oriented structures like fibers, the signal magnitude depends on the relative orientation between fiber and gratings. This allows to analytically reconstruct the fiber orientations at a micrometer scale. However, there currently exists no implementation of a clinically feasible trajectory for recovering the full 3D orientation of a fiber. In principle, a helical trajectory can be suitable for this task. However, as a first step towards dark-field imaging in a helix, a careful analysis of the signal formation is required. Towards this goal, we study in this paper the impact of the grating orientation. We use a recently proposed 3D-projection model and show that the projected dark-field scattering at a single volume point depends on the grating sensitivity direction and the helix geometry. More specifically, the dark-field signal on a 3D trajectory always consists of a linear combination of a constant and an angular-dependent component.
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- 2019
7. Quality of information disclosure, property rights, and bank loans: A bank heterogeneity perspective
- Author
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Xing Liu, Shiyang Hu, Xichan Chen, and Wanli Li
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050208 finance ,media_common.quotation_subject ,PSM ,05 social sciences ,Perspective (graphical) ,Information quality ,Financial system ,Context (language use) ,050201 accounting ,Commit ,lcsh:HF5601-5689 ,Property rights ,Quality of information disclosure ,lcsh:Accounting. Bookkeeping ,Accounting ,0502 economics and business ,ddc:650 ,Quality (business) ,Business ,Empirical evidence ,China ,Bank loans ,Finance ,media_common - Abstract
Using the context of the financial reform and the development of the non-state sector in China in the past decade, we examine the roles that the quality of information disclosure and property rights play in the allocation of different types of bank credit. We find that foreign banks and policy banks exercise “financial discrimination,” and that local commercial banks, large state-owned commercial banks, national joint-stock banks, local city commercial banks, and rural commercial banks not only exercise financial discrimination but also provide significant “financial support” to non-state-owned enterprises by providing more lending opportunities and larger loans. However, when enterprises commit information disclosure violations, the local commercial banks, national joint-stock banks, local city commercial banks, and rural commercial banks reverse their credit decisions and begin to exercise financial discrimination against non-state-owned enterprises. At the same time, large state-owned commercial banks continue to provide financial support to non-state-owned enterprises. We also find that the quality of the information disclosed by enterprises has a moderating effect rather than an intermediary effect on the relationship between property rights and bank loans. Overall, the results of this paper shine new light on the market-oriented reform of the banking industry, and provide new empirical evidence for the presence of financial discrimination in the supply of bank credit. Our findings also have practical implications for solving the financing difficulties of non-state-owned enterprises. Keywords: Quality of information disclosure, Property rights, Bank loans, PSM
- Published
- 2019
8. Secure communication in cooperative network with wireless information and power transfer
- Author
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Zhiguo Ding and Shiyang Hu
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business.industry ,Computer science ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Power (physics) ,law.invention ,Constraint (information theory) ,Secure communication ,Relay ,law ,Signal Processing ,Computer Science::Networking and Internet Architecture ,Wireless ,Maximum power transfer theorem ,Relaxation (approximation) ,Electrical and Electronic Engineering ,business ,Energy harvesting ,Computer Science::Information Theory ,Computer network - Abstract
This paper considers the secure communication issue in an amplify-and-forward relaying cooperative network, in which the energy harvesting relay is powered by radio-frequency signals from the source. Based on the two different energy harvesting strategies, that is, power splitting-based relaying protocols and time switching-based relaying protocols, the authors formulate the problem for maximising the secrecy rate subject to the transmitted power constraint by taking into account the power splitting coefficient and time switching coefficient. The authors solve these problems by applying the semi-definite programming relaxation approach and 1D optimisation over the coefficients of energy harvesting protocols. The simulation results are presented to verify the effectiveness of these solutions proposed in this study.
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- 2015
9. Do political connection disruptions increase labor costs in a government-dominated market? Evidence from publicly listed companies in China
- Author
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Shiyang Hu, Chunyan Wei, and Feng Chen
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040101 forestry ,Economics and Econometrics ,Labour economics ,Government ,050208 finance ,Strategy and Management ,media_common.quotation_subject ,05 social sciences ,04 agricultural and veterinary sciences ,Politics ,Turnover ,0502 economics and business ,8. Economic growth ,Unemployment ,0401 agriculture, forestry, and fisheries ,Business ,Business and International Management ,China ,Productivity ,Finance ,Labor cost ,Communism ,media_common - Abstract
This paper investigates whether the disruption of political connections increases labor costs among Chinese listed firms. Using the Communist Party of China's Rule No. 18 as an exogenous shock that forces firms to lose their politically connected independent directors, we find that the disruption of political connections is associated with an increase in labor costs (both in terms of aggregate labor costs per firm and average labor costs per employee) and an increase in employee turnover. Such increases do not lead to labor productivity improvements, and cannot be attributed to changes in corporate policies or the composition of labor forces after Rule No. 18. We also find that firms with higher unemployment risk and skilled labor risk increase their labor costs to a larger extent. Our results are robust to alternative labor cost measures, controlling for potential confounding events, and alternative political connection channels. Our study shows an unintended labor market consequence—increases in labor costs—of political connection disruptions for firms that are adversely affected by such disruptions.
- Published
- 2020
10. X-ray Phase Contrast: Research on a Future Imaging Modality
- Author
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Lina Felsner, Sebastian Kaeppler, Johannes Bopp, Shiyang Hu, and Christian Riess
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Sight ,Modality (human–computer interaction) ,Optics ,Field (physics) ,law ,business.industry ,Computer science ,Phase contrast microscopy ,Medical imaging ,business ,law.invention - Abstract
Modern medical imaging is achieved with state-of-the-art devices, that use cutting-edge technology from different fields of engineering. Oftentimes, progress is driven by discoveries in a at first sight seemingly unrelated field of research.
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- 2018
11. Towards quantification of kidney stones using X-ray dark-field tomography
- Author
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Rolf Kaufmann, Michele Griffa, Andreas Maier, Gisela Anton, Fei Yang, Christian Riess, and Shiyang Hu
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medicine.medical_specialty ,High prevalence ,business.industry ,Ultrasound ,Iterative reconstruction ,medicine.disease ,01 natural sciences ,Imaging phantom ,030218 nuclear medicine & medical imaging ,010309 optics ,03 medical and health sciences ,0302 clinical medicine ,Two kidney ,Homogeneous ,0103 physical sciences ,Medicine ,Kidney stones ,Tomography ,Radiology ,business - Abstract
Kidney stones is a renal disease with high prevalence and one of the major reasons for emergency room visits. The prevalence of kidney stones is increasing, and the lifetime recurrence rate is estimated as almost 50%. Thus, treatment of kidney stones becomes an increasingly important topic. However, different types of kidney stones require specific treatments, which creates the need for accurate diagnosis of the stone type prior to the intervention. Imaging techniques that are commonly used for the detection of kidney stones, such as X-ray CT and ultrasound, are insufficient to differentiate the types of kidney stones. In this paper, we present a proof-of-concept study for differentiating kidney stones using X-ray dark-field tomography. The most important advantage of this method is its ability to image non-homogeneous kidney stones, i.e., to localize and identify the individual components of mixed-material kidney stones. We use a weighted total-variation regularized reconstruction method to compute the ratio of dark-field over absorption signal (DA Ratio) from noisy projections. We evaluate the performance of the proposed approach on two kidney stones of homogeneous composition, and one well-defined numerical phantom with known ground truth for mixed types of stones. We illustrate that the DA Ratio is significantly distinguished for different materials from the experiments. Reconstruction of phantom data recovers voxel-wise material information with high accuracy. We show that X-ray dark-field tomography has a significant potential in selective characterization of kidney stones.
- Published
- 2017
12. Reconstruction of scalar and vectorial components in X-ray dark-field tomography
- Author
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Gisela Anton, Andreas Maier, Thilo Michel, Thomas Weber, Florian Bayer, Christian Riess, and Shiyang Hu
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Materials science ,Arachis ,genetic structures ,Biomedical Technology ,Grating ,computer.software_genre ,Signal ,Optics ,Voxel ,Nondestructive testing ,Medical imaging ,Scattering, Radiation ,Tomography ,Multidisciplinary ,Phantoms, Imaging ,business.industry ,Orientation (computer vision) ,X-Rays ,Scalar (physics) ,Models, Theoretical ,Wood ,Interferometry ,Physical Sciences ,Anisotropy ,Radiographic Image Interpretation, Computer-Assisted ,sense organs ,business ,computer ,Algorithms - Abstract
Grating-based X-ray dark-field imaging is a novel technique for obtaining image contrast for object structures at size scales below setup resolution. Such an approach appears particularly beneficial for medical imaging and nondestructive testing. It has already been shown that the dark-field signal depends on the direction of observation. However, up to now, algorithms for fully recovering the orientation dependence in a tomographic volume are still unexplored. In this publication, we propose a reconstruction method for grating-based X-ray dark-field tomography, which models the orientation-dependent signal as an additional observable from a standard tomographic scan. In detail, we extend the tomographic volume to a tensorial set of voxel data, containing the local orientation and contributions to dark-field scattering. In our experiments, we present the first results of several test specimens exhibiting a heterogeneous composition in microstructure, which demonstrates the diagnostic potential of the method.
- Published
- 2014
13. Beamforming optimization for full-duplex cooperative cognitive radio networks
- Author
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Shiyang Hu, Zhiguo Ding, Qiang Ni, and Yi Yuan
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Beamforming ,Semidefinite programming ,Engineering ,Optimization problem ,business.industry ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Transmitter ,020206 networking & telecommunications ,Data_CODINGANDINFORMATIONTHEORY ,02 engineering and technology ,law.invention ,Cognitive radio ,Relay ,law ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Fading ,business ,Communication channel ,Computer network - Abstract
This paper considers the problem of beamforming optimization in a cognitive cooperative energy harvesting network, in which the secondary transmitter (ST) harvests energy from the primary transmitter (PT) and relays the information for the primary user (PU) with amplify-and-forward (AF) relay protocol. When the channel of the primary system is affected with deep fading or shadowing effects, the ST can assist the primary information transmission. It is particularly useful to employ the energy harvesting protocol to avoid that the ST does not have enough energy to assist the PU. Based on the self-energy recycling relay protocol, we study the beamforming optimization problem. We develop a semidefinite programming (SDP) relaxation method to solve the proposed problem. We also use SDP and one-dimension (1-D) optimization to solve the beamforming optimization based on a time-switching relaying protocol (TSR) as a benchmark. The simulation results are presented to verify that the self-energy recycling protocol achieves a significant rate gain compared to the TSR protocol and the power-splitting relaying (PSR) protocol.
- Published
- 2016
14. Energy efficiency in energy harvesting cooperative networks with self-energy recycling
- Author
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Zhiguo Ding, Qiang Ni, Shiyang Hu, Wenjuan Yu, and Zhengyu Song
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Mathematical optimization ,Optimization problem ,business.industry ,Computer science ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Cooperative diversity ,law.invention ,Fractional programming ,Relay ,law ,Computer Science::Networking and Internet Architecture ,Wireless ,business ,Telecommunications ,Energy harvesting ,Energy (signal processing) ,Computer Science::Information Theory ,Efficient energy use - Abstract
Cooperative communication has been identified as an important component in the 5G system. This paper considers a decode-and-forward (DF) relaying wireless cooperative network, in which the self-energy recycling relay is powered by radio-frequency (RF) signal from the source and its transmitted power from the loop-back channel. The harvested energy is used to support the relay transmissions. Based on a self-energy recycling relaying protocol, we study the optimization of energy efficiency in wireless cooperative networks. Although the formulated optimization problem is not convex, it can be re-constructed to a parametric problem in the convex form by using the non-linear fractional programming, to which closed form solutions can be found by using the Lagrange multiplier method. The simulation results are presented to verify the effectiveness of this solution proposed in this paper.
- Published
- 2015
15. Energy-efficient optimization in cooperative networks with wireless information and power transfer
- Author
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Zhiguo Ding, Shiyang Hu, and Xuehong Cao
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Optimization problem ,Computer science ,business.industry ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,law.invention ,Relay ,law ,Computer Science::Networking and Internet Architecture ,Electronic engineering ,Maximum power transfer theorem ,Wireless ,Telecommunications ,business ,Energy harvesting ,Energy (signal processing) ,Computer Science::Information Theory ,Efficient energy use - Abstract
This paper considers a decode-and-forward (DF) relaying wireless cooperative network, in which the energy harvesting relay is powered by radio-frequency (RF) signal from the source and then the harvested energy is used to support the relay transmissions. Based on the two different energy harvesting strategies, i.e. time switching-based relaying (TSR) protocols and power splitting-based relaying (PSR) protocols, we study the optimization of energy efficiency in wireless cooperative networks. Although the formulated optimization problem is not convex, it can be re-constructed in a convex form by using the non-linear fractional programming, to which closed form solutions can be found by using the Lagrange multiplier method. The simulation results are presented to verify the effectiveness of this solution proposed in this paper.
- Published
- 2015
16. 3D Tensor Reconstruction in X-Ray Dark-Field Tomography
- Author
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Joachim Hornegger, Florian Bayer, Thomas Weber, Gisela Anton, Christian Riess, Andreas Maier, Shiyang Hu, and Peter Fischer
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Physics ,Ground truth ,Tomographic reconstruction ,Transformation (function) ,Orientation (computer vision) ,business.industry ,Coordinate system ,Computer vision ,Artificial intelligence ,Tensor ,Tomography ,business ,Imaging phantom - Abstract
X-ray dark-field imaging is a novel technique which provides complementary information on structural variation and density fluctuation. It allows to obtain object structures at micrometer scale and also contains information on the orientation of these structures. Since it can be acquired by a conventional X-ray imaging system, dark-field imaging has great potential for medical diagnosis. However, fully recovering 3D orientations in dark-field reconstruction still remains unexplored. In this paper, we propose an improved reconstruction method based on the zero-constrained dark-field reconstruction by Bayer et al. and a simplified principle axes transformation. A well-defined phantom containing representative 3D orientations is reconstructed in our experiment. On average, the structure orientations in the reconstructed volume differ from the ground truth by 9%. Within the boundaries of an object, the error drops to 6%. Application of this method in real diagnosis data can be expected in future.
- Published
- 2015
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