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28 results on '"Cheng, Shaoyi"'

2. Research on the Structural, Mechanical and Corrosion Tribological Properties of CoCrMo and CoCrMoW Alloys in Calf Serum Solution

Author

WANG Jiang, MA Yutian, CHENG Shaoyi, ZHANG Dong, MENG Junhu, XIN Benbin

Subjects
cocrmo series alloys； microstructure； mechanical properties； corrosion tribological properties； corrosion and wear resistance mechanism, Materials of engineering and construction. Mechanics of materials, TA401-492, Technology
Abstract

In order to clarify the corrosion friction behavior and corrosion wear resistance mechanism of CoCrMo and CoCrMoW alloys in calf serum solution, CoCrMo and CoCrMoW alloys were prepared using the vacuum melting technique, and the microstructure, mechanical and corrosion tribological properties of the two alloys were investigated by means of scanning electron microscopy(SEM),energy-dispersive spectroscopy(EDS) , transmission electron microscope(TEM), X-ray diffraction(XRD), compression mechanical performance experiments and corrosion wear tests.Results showed that the two alloys were composed of γ-Co and ε-Co, and the microstructure was dominated by equiaxial crystals.CoCrMo alloy exhibited excellent compressive mechanical properties and good corrosion resistance in calf serum solution,while pitting corrosion occurred in the CoCrMoW alloy.The two alloys showed good corrosion tribological properties in calf serum solution, with friction coefficients and wear rates of 0.11 ～0.21 and 1.01×10－6 ～2.46×10－6 mm3/(N·m), respectively.The friction coefficients of the two alloys decreased with the increase in load and frequency, and the stability of real-time friction coefficients increased.At low loads, the corrosive wear resistance of the alloys increased with frequency, and their wear mechanisms were dominated by abrasive wear.At high loads, the wear rate of the alloys increased with frequency,and abrasive wear and corrosive wear coexisted.Overall,the corrosion wear resistance of CoCrMo alloy was better than that of CoCrMoW alloy, which was mainly due to the better compressive mechanical properties and corrosion resistance of CoCrMo alloys.

Published
2024
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4. Research on the Two-path Influence of Employee Feedback Orientation on Feedback Seeking Strategy Under the Framework of Cost-value Based on Structural Equation Model

Author

Yu, Fang, Cheng, Shaoyi, Yu, Zhen, Wu, Yingyu, Li, Kan, Editor-in-Chief, Li, Qingyong, Associate Editor, Fournier-Viger, Philippe, Series Editor, Hong, Wei-Chiang, Series Editor, Liang, Xun, Series Editor, Wang, Long, Series Editor, Xu, Xuesong, Series Editor, Khan, Syed Abdul Rehman, editor, Jhanjhi, Noor Zaman, editor, and Li, Hongbo, editor

Published
2023
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10. Structured Deep Neural Network Pruning via Matrix Pivoting

Author

Sredojevic, Ranko, Cheng, Shaoyi, Supic, Lazar, Naous, Rawan, and Stojanovic, Vladimir

Subjects
Computer Science - Learning
Abstract

Deep Neural Networks (DNNs) are the key to the state-of-the-art machine vision, sensor fusion and audio/video signal processing. Unfortunately, their computation complexity and tight resource constraints on the Edge make them hard to leverage on mobile, embedded and IoT devices. Due to great diversity of Edge devices, DNN designers have to take into account the hardware platform and application requirements during network training. In this work we introduce pruning via matrix pivoting as a way to improve network pruning by compromising between the design flexibility of architecture-oblivious and performance efficiency of architecture-aware pruning, the two dominant techniques for obtaining resource-efficient DNNs. We also describe local and global network optimization techniques for efficient implementation of the resulting pruned networks. In combination, the proposed pruning and implementation result in close to linear speed up with the reduction of network coefficients during pruning., Comment: 16 pages, 3 figures, 2 tables, 1 listing

Published
2017

12. High Level Synthesis with a Dataflow Architectural Template

Author

Cheng, Shaoyi and Wawrzynek, John

Subjects
Computer Science - Hardware Architecture
Abstract

In this work, we present a new approach to high level synthesis (HLS), where high level functions are first mapped to an architectural template, before hardware synthesis is performed. As FPGA platforms are especially suitable for implementing streaming processing pipelines, we perform transformations on conventional high level programs where they are turned into multi-stage dataflow engines [1]. This target template naturally overlaps slow memory data accesses with computations and therefore has much better tolerance towards memory subsystem latency. Using a state-of-the-art HLS tool for the actual circuit generation, we observe up to 9x improvement in overall performance when the dataflow architectural template is used as an intermediate compilation target., Comment: Presented at 2nd International Workshop on Overlay Architectures for FPGAs (OLAF 2016) arXiv:1605.08149

Published
2016

13. How Energy Dissipation Mode Controls the Evolution of Multiple Plane‐Strain Hydraulic Fractures Under Isotropic Stresses.

Author

Cheng, Shaoyi, Wu, Bisheng, Zhang, Xi, Huppert, Herbert E., and Jeffrey, Robert G.

Subjects
*HYDRAULIC fracturing, *VISCOUS flow, *FLUID flow, *ROCK deformation, *FRACTURING fluids
Abstract

The geometrical prediction of multiple hydraulic fractures fed from a single fluid source is a major challenge due to transient stress interference among fractures and nonlinear coupling between rock deformation and fluid flow. Here we find that the evolution of multiple hydraulic fractures under isotropic stresses is controlled by a dimensionless toughness, which measures the ratio of the energy dissipated in rock fracturing to that dissipated in viscous fluid flow. The existence of a relation between the dimensionless toughness and the dimensionless length of the arrested fractures is demonstrated by using a bifurcation analysis. The numerical results show that the fractures tend to grow simultaneously in the viscosity‐dominated regime, and the scaling remains effective when the number of fractures varies. This study provides a quantitative and efficient tool for predicting the fracture pattern in engineered and natural fracture systems. Plain Language Summary: The formation of multiple fluid‐driven fractures fed from a single fluid source is ubiquitous in geological features such as sub‐parallel dyke swarms and hydraulic fractures in reservoirs. Due to the stress interference exerted by neighboring fractures, the growth of multiple fractures is not uniform, which finally leads to a complex fracture system. However, the geometrical prediction of such fracture system is a major challenge, and a general understanding in the evolution of the fracture system is lacking. In this study, we investigate the controlling factors in the propagation of multiple hydraulic fractures by using theoretical and numerical techniques. A relation is found between the fracture pattern and a dimensionless number that accounts for the energy dissipation between rock fracturing and fluid flow. Numerical results show that the scaling remains effective when the number of fractures varies under isotropic stresses, and the fractures tend to grow simultaneously when the energy is mainly dissipated in fluid flow, while the uniform fracture growth is suppressed when the energy is mainly dissipated in rock fracturing. This work provides insights into the mechanics controlling the evolution of multiple hydraulic fractures and offers an efficient method in predicting the fracture geometry in engineering applications. Key Points: A quantitative relation is found between a dimensionless number and the pattern of multiple plane‐strain hydraulic fracturesA uniform fracture growth is favored when energy is mostly dissipated in fluid flow instead of rock fracturingThe scaling remains effective for different number of hydraulic fractures under isotropic stresses [ABSTRACT FROM AUTHOR]

Published
2024
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18. Accelerator Synthesis and Integration for CPU+FPGA Systems

Author

Cheng, Shaoyi

Subjects
Computer science, Binary instrumentation, FPGA, Heterogeneous computing, High level synthesis, Parallelization, Process Network
Abstract

As the scaling down of transistor size no longer provides boost to processor clock frequency, there has been a move towards parallel computers and more recently, heterogeneous computing platforms. To target the FPGA component in these systems, high-level synthesis (HLS) tools were developed to facilitate hardware generation from higher level algorithmic descriptions. Despite being an effective method for rapid hardware generation, in the context of offloading compute intensive software kernels to FPGA accelerators, current HLS tools do not always take full advantage of the hardware platforms. Processor centric software implementations often have to be rewritten if good quality of results is desired.In this work, we present a framework to refactor and restructure compute intensive software kernels, making them better suited for FPGA platforms. An algorithm was proposed to decouple memory operations and computation, generating accelerator pipelines composed of independent modules connected through FIFO channels. These decoupled computational pipelines have much better throughput due to their efficient use of the memory bandwidth and improved tolerance towards data access latency. Our methodology complements existing work in high-level synthesis and facilitates the creation of heterogeneoussystems with high performance accelerators and general purpose processors. With our approach, for a set of non-regular algorithm kernels written in C, a performance improvement of 3.3 to 9.1x is observed over direct C-to-Hardware mapping using a state-of-the-art HLS tool. To ensure the absence of artificial deadlocks in the pipelines generated by our framework, we also formulated an analysis scheme examining various dependencies between operations distributed across different pipeline modules. The interactions between the modules' schedules, the capacity of the communication channels and the memory access mechanisms are all incorporated into our model, such that potential artificial deadlocks can be detected and resolved a priori. The applicability of our technique is not limited to the computational pipeline generated by our algorithm, but also other networks of communicating processes assuming their interaction with the channels follows a set of simple rules.To push the limit in usability of FPGA platforms, we also explored the generation and integration of accelerators using only program binaries and execution profiles. Assuming no user input, the approach is only applied to more regular applications, where the memory access patterns are analyzable and coarse grained parallelism can be extracted. A run time mechanism is also devised to ensure the correctness of the parallelization performed during accelerator synthesis. With the help of binary instrumentation tools, it becomes possible to integrate the FPGA-accelerated parts into the original application in a user transparent way. Neither recompilation of the original program nor the source code is required. This approach is applied to a few benchmarks for which decoupled computational pipelines are synthesized. With memory level and coarse grained parallelization, significant improvement in performance (3.7 to 9x) over general purpose processor was observed, despite the FPGA running at a fraction of the CPU's clock frequency. The run time checking mechanism was also shown to only incur small overhead, especially for loop nests with large number of iterations.

Published
2016

19. Microscale Damage Induced by CO2Storage on the Microstructure of Sandstone Coupling Hydro–Mechanical–Chemical Processes

Author

Nie, Yuanxun, Wu, Bisheng, Zhang, Guangqing, Zhang, Li, Lei, Zhengda, Cheng, Shaoyi, Zhang, Haitao, and Li, Shiyuan

Abstract

A good understanding of CO2–brine–rock interactions that cause microscale damage to the microstructure of sandstone, affecting pore fluid transport and reservoir stability, is important for studying storage efficiency during CO2storage. In this study, the equipment is first designed to saturate rock samples using CO2–brine under in situ conditions and then the homogeneous and heterogeneous sandstone samples are saturated for 30 days with and without the confining pressure (20 MPa). Through scanning electron microscopy (SEM) observation and analysis, it is found that the confining pressure reduces the degree of damage in various scales from micrometer to millimeter, such as reducing the mineral dissolution, decreasing the induced swelling of the bedding planes, and causing some pores to collapse. The nuclear magnetic resonance results show that the change in porosity is mainly caused by the increase in the number of relatively small-sized (characterized in terms of fluid relaxation time T2< 10–3s) pores after CO2–brine saturation. In addition, the alterations of the pore system in homogeneous and heterogeneous sandstones are different, such as a larger increase in the porosity of homogeneous sandstone (by 5.29%). In heterogeneous sandstone, the effect of mineral dissolution induced by chemical reactions on damaging the microstructure is more obvious than mineral swelling. In addition, it is found that the CO2–brine saturation decreases the fractal dimension of the sandstone by nearly 2%, increasing the pore connectivity. This study is helpful for understanding the evolution of the sandstone microstructure under geological conditions during the long-term CO2storage process.

Published
2022
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