An investigation on the cooling characteristics of impingement-reversed convection film cooling in a curved section

Weihua Yang,Xiangli Li,Xue Liu 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5

An experiment was designed at the curving section of a combustion chamber to study the effects of cooling effectiveness on impingement-reversed convection film cooling with and without pin fins. Numerical simulations were also carried out. The effectiveness of compound cooling increased with the rise in blowing ratio. With regard to the effect of the pin fins, impingement pin fin-reversed convectionfilm cooling was more effective than the method without pin fins, particularly for smaller blowing ratio conditions. The number and arrangement of fin pin rows had a small effect on cooling efficiency under the same blowing ratio value. Simulation results agreed well with experimental data and could be used to optimize basic design.

Privacy Protection Method for Sensitive Weighted Edges in Social Networks

( Weihua Gong ),( Rong Jin ),( Yanjun Li ),( Lianghuai Yang ),( Jianping Mei ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.2

Privacy vulnerability of social networks is one of the major concerns for social science research and business analysis. Most existing studies which mainly focus on un-weighted network graph, have designed various privacy models similar to k-anonymity to prevent data disclosure of vertex attributes or relationships, but they may be suffered from serious problems of huge information loss and significant modification of key properties of the network structure. Furthermore, there still lacks further considerations of privacy protection for important sensitive edges in weighted social networks. To address this problem, this paper proposes a privacy preserving method to protect sensitive weighted edges. Firstly, the sensitive edges are differentiated from weighted edges according to the edge betweenness centrality, which evaluates the importance of entities in social network. Then, the perturbation operations are used to preserve the privacy of weighted social network by adding some pseudo-edges or modifying specific edge weights, so that the bottleneck problem of information flow can be well resolved in key area of the social network. Experimental results show that the proposed method can not only effectively preserve the sensitive edges with lower computation cost, but also maintain the stability of the network structures. Further, the capability of defending against malicious attacks to important sensitive edges has been greatly improved.

Adaptive Cross-Layer Resource Optimization in Heterogeneous Wireless Networks with Multi-Homing User Equipments

Weihua Wu,Qinghai Yang,Bingbing Li,곽경섭 한국통신학회 2016 Journal of communications and networks Vol.18 No.5

In this paper, we investigate the resource allocation prob-lemin time-varying heterogeneous wireless networks (HetNet) withmulti-homing user equipments (UE). The stochastic optimizationmodel is employed tomaximize the network utility, which is definedas the difference between the HetNet’s throughput and the total en-ergy consumption cost. In harmony with the hierarchical architec-ture of HetNet, the problem of stochastic optimization of resourceallocation is decomposed into two subproblems by the Lyapunovoptimization theory, associated with the flow control in transportlayer and the power allocation in physical (PHY) layer, respec-tively. For avoiding the signaling overhead, outdated dynamic in-formation, and scalability issues, the distributed resource alloca-tion method is developed for solving the two subproblems based onthe primal-dual decomposition theory. After that, the adaptive re-source allocation algorithm is developed to accommodate the time-varying wireless network only according to the current networkstate information, i.e. the queue state information (QSI) at radioaccess networks (RAN) and the channel state information (CSI) ofRANs-UE links. The tradeoff between network utility and delay isderived, where the increase of delay is approximately linear in Vand the increase of network utility is at the speed of 1/V with acontrol parameter V . Extensive simulations are presented to showthe effectiveness of our proposed scheme.

USP13 promotes proliferation and angiogenesis of diffuse large B-cell lymphoma cells by promoting MCL-1 expression

Yang Huiyun,Chen Tianping,Fan Minxia,Xu Weihua,Wu Xiuwei 대한독성 유전단백체 학회 2024 Molecular & cellular toxicology Vol.20 No.3

Background Diffuse large B-cell lymphoma (DLBCL) is a diffuse malignant hyperplastic disease of large B-cell lymphoma characterized by high heterogeneous and aggressiveness and has a poor prognosis. Objectives To explore the pathogenesis of DLBCL and identify the effective therapeutic targets. Results The expression of ubiquitin-specific peptidase 13 (USP13) was significantly increased in peripheral blood of children with DLBCL and in DLBCL cells. USP13 overexpression promoted the capacity of proliferation, migration, invasion of DLBCL cells and human umbilical vein endothelial cell (HUVEC) tube formation, while knockdown of USP13 suppressed the proliferation, migration, invasion, and angiogenesis of DLBCL cells. USP13 positively regulated the expression of myeloid cell leukemia 1 (MCL-1) in DLBCL cells. Overexpression of MCL-1 attenuated the inhibition effects of USP13 knockdown on DLBCL cells. Conclusion USP13 modulated DLBCL cell proliferation, migration, invasion, and angiogenesis by promoting MCL-1 expression. Background Diffuse large B-cell lymphoma (DLBCL) is a diffuse malignant hyperplastic disease of large B-cell lymphoma characterized by high heterogeneous and aggressiveness and has a poor prognosis. Objectives To explore the pathogenesis of DLBCL and identify the effective therapeutic targets. Results The expression of ubiquitin-specific peptidase 13 (USP13) was significantly increased in peripheral blood of children with DLBCL and in DLBCL cells. USP13 overexpression promoted the capacity of proliferation, migration, invasion of DLBCL cells and human umbilical vein endothelial cell (HUVEC) tube formation, while knockdown of USP13 suppressed the proliferation, migration, invasion, and angiogenesis of DLBCL cells. USP13 positively regulated the expression of myeloid cell leukemia 1 (MCL-1) in DLBCL cells. Overexpression of MCL-1 attenuated the inhibition effects of USP13 knockdown on DLBCL cells. Conclusion USP13 modulated DLBCL cell proliferation, migration, invasion, and angiogenesis by promoting MCL-1 expression.

Bias process for heteroepitaxial diamond nucleation on Ir substrates

Wang Weihua,Yang Shilin,Liu Benjian,Hao Xiaobin,Han Jiecai,Dai Bing,Zhu Jiaqi 한국탄소학회 2023 Carbon Letters Vol.33 No.2

Heteroepitaxy is a better method of enlarging SCD wafer size than homoepitaxy. In this work, several aspects of the bias process for heteroepitaxial diamond nucleation are studied experimentally. First, with increasing bias time, the diamond-nucleation pathway is found to transform from “isolated-crystal nucleation” to “typical domain-nucleation” and back to “isolated-crystal nucleation.” An interdependent relationship between bias voltage and bias time is proposed: the higher the bias voltage, the shorter the bias time. Second, a correlation exists between the threshold bias voltage and reactor-chamber pressure: a higher reactor chamber pressure usually requires a higher threshold bias voltage to realize “typical domain nucleation.” Third, diamond bias-enhanced nucleation and growth is observed at a high CH4 content, where the dynamic equilibrium between amorphous-carbon-layer deposition and atomic-hydrogen etching is broken. Finally, epitaxial nucleation is obtained on a substrate with ∅30 mm in a home-made MPCVD setup.

Energy-Efficient Traffic Splitting for Time-Varying Multi-RAT Wireless Networks

Wu, Weihua,Yang, Qinghai,Gong, Peng,Kwak, Kyung Sup IEEE 2017 IEEE Transactions on Vehicular Technology VT Vol.66 No.7

<P>This paper investigates the energy-efficient traffic splitting for time-varying wireless networks, which have been configured with multiple radio access technologies (multi-RATs). A single stream of the media content is split into multiple segments, which could be transmitted over multiple RATs simultaneously so that the complementary advantages of different RATs can be exploited. To address this problem, we formulate the traffic splitting as a long-term energy efficiency (EE) maximization problem with respect to the time-varying channel state information (CSI). An equivalent transformation method is proposed to convert the long-term nonconvex EE maximization problem into a concave optimization. To reduce the computational complexity, we develop a dynamic traffic splitting (DTS) algorithm, which iterates only one time when the network state changes. Then, we use the definition of tracking error to describe the difference between the DTS and the target optimal traffic splitting solution. After that, an adaptive-compensation traffic splitting (ACTS) algorithm is proposed to offset the tracking error so as to enhance the EE performance. More specifically, we give a sufficient condition for significantly eliminating the tracking errors of the ACTS algorithm. Simulation results show that the proposed ACTS algorithm obtains the EE performance comparable with the optimal solution at the overhead of only a single iteration at each timeslot of the network state acquisition.</P>

Optimizing the Imaging Protocol for Ex Vivo Coronary Artery Wall Using High-Resolution MRI: An Experimental Study on Porcine and Human

Jiong Yang,Tao Li,Xiaoming Cui,Weihua Zhou,Xin Li,Xinwu Zhang 대한영상의학회 2013 Korean Journal of Radiology Vol.14 No.4

Objective: To optimize the MR imaging protocol for coronary arterial wall depiction in vitro and characterize the coronary atherosclerotic plaques. Materials and Methods: MRI examination was prospectively performed in ten porcine hearts in order to optimize the MR imaging protocol. Various surface coils were used for coronary arterial wall imaging with the same parameters. Then, the image parameters were further optimized for high-resolution coronary wall imaging. The signal-noise ratio (SNR) and contrast-noise ratio (CNR) of images were measured. Finally, 8 human cadaver hearts with coronary atherosclerotic plaques were prospectively performed with MRI examination using optimized protocol in order to characterize the coronary atherosclerotic plaques. Results: The SNR and CNR of MR image with temporomandibular coil were the highest of various surface coils. High-resolution and high SNR and CNR for ex vivo coronary artery wall depiction can be achieved using temporomandibular coil with 512 x 512 in matrix. Compared with histopathology, the sensitivity and specificity of MRI for identifying advanced plaques were: type IV-V (lipid, necrosis, fibrosis), 94% and 95%; type VI (hemorrhage), 100% and 98%; type VII (calcification), 91% and 100%; and type VIII (fibrosis without lipid core), 100% and 98%, respectively. Conclusion: Temporomandibular coil appears to be dramatically superior to eight-channel head coil and knee coil for ex vivo coronary artery wall imaging, providing higher spatial resolution and improved the SNR. Ex vivo high-resolution MRI has capability to distinguish human coronary atherosclerotic plaque compositions and accurately classify advanced plaques.

Adaptive Cross-Layer Resource Optimization in Heterogeneous Wireless Networks with Multi-Homing User Equipments

Wu, Weihua,Yang, Qinghai,Li, Bingbing,Kwak, Kyung Sup The Korea Institute of Information and Commucation 2016 Journal of communications and networks Vol.18 No.5

In this paper, we investigate the resource allocation problem in time-varying heterogeneous wireless networks (HetNet) with multi-homing user equipments (UE). The stochastic optimization model is employed to maximize the network utility, which is defined as the difference between the HetNet's throughput and the total energy consumption cost. In harmony with the hierarchical architecture of HetNet, the problem of stochastic optimization of resource allocation is decomposed into two subproblems by the Lyapunov optimization theory, associated with the flow control in transport layer and the power allocation in physical (PHY) layer, respectively. For avoiding the signaling overhead, outdated dynamic information, and scalability issues, the distributed resource allocation method is developed for solving the two subproblems based on the primal-dual decomposition theory. After that, the adaptive resource allocation algorithm is developed to accommodate the timevarying wireless network only according to the current network state information, i.e. the queue state information (QSI) at radio access networks (RAN) and the channel state information (CSI) of RANs-UE links. The tradeoff between network utility and delay is derived, where the increase of delay is approximately linear in V and the increase of network utility is at the speed of 1/V with a control parameter V. Extensive simulations are presented to show the effectiveness of our proposed scheme.

Comparative Effects and Safety of Full-Endoscopic Versus Microscopic Spinal Decompression for Lumbar Spinal Stenosis: A Meta-Analysis and Statistical Power Analysis of 6 Randomized Controlled Trials

Zechuan Yang,Huan Wang,Wenkai Li,Weihua Hu 대한척추신경외과학회 2022 Neurospine Vol.19 No.4

Objective: This meta-analysis with statistical power analysis aimed to evaluate the difference between full-endoscopic and microscopic spinal decompression in treating spinal stenosis. Methods: We searched PubMed, Embase, CENTRAL (Cochrane Central Register of Controlled Trials), and CNKI (China National Knowledge Infrastructure) for relevant randomized controlled trials (RCTs) regarding the comparison of full-endoscopic versus microscopic spinal decompression in treating lumbar spinal stenosis through February 28, 2022. Two independent investigators selected studies, extracted information, and appraised methodological quality. Meta-analysis was conducted using RevMan 5.4 and STATA 14.0, and statistical power analysis was performed using G*Power 3.1. Results: Six RCTs involving 646 patients met selection criteria. Meta-analysis suggested that, compared with microscopic decompression, full-endoscopic spinal decompression achieved more leg pain improvement (mean difference [MD], -0.20; 95% confidence interval [CI], -0.30 to -0.10; p = 0.001), shortened operative time (MD, -12.71; 95% CI, -18.27 to -7.15; p < 0.001), and decreased the incidence of complications (risk ratio, 0.43; 95% CI, 0.22–0.82; p = 0.01), which was supported by a statistical power of 98.57%, 99.97%, and 81.88%, respectively. Conclusion: Full-endoscopic spinal decompression is a better treatment for lumbar spinal stenosis, showing more effective leg pain improvement, shorter operative time, and fewer complications than microscopic decompression.

Study of microstructure evolution and mechanical behaviour changes of PAN-based carbon fibers after high-temperature heat treatment (up to 2950 °C)

Lichao Song,Weihua Xie,Dong Yu,Songhe Meng,Fan Yang,Fengliang Liu,Ying Zhang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.124 No.-

The quantitative relationship between the microstructure behaviour and mechanical properties of polyacrylonitrile(PAN) carbon fibers (CF) after being heat treated in the range of 2000–2950 C was studied. The surface morphology, elemental composition, orientation of graphite microcrystallites (P), carboninterlayer spacing distances (d002), crystallite dimension (Lc and La), skin-core structure, pore structureand mechanical properties were characterised and evaluated after high-temperature heat treatment(HHT). The study found that increasing temperature resulted in an increase in the orientation of graphitecrystals and the stress component of microcrystalline strong bonding direction along the fiber axial direction,leading to Young’s modulus of T300 and M40J increases of 18.7% and 7.7%, respectively. Meanwhile,the decrease in tensile strength by 53.9% and 29.4%, respectively, can be attributed to the deterioration ofthe homogeneity of the CF radial structure and a reduction in the stress dissipation path inside the CF. Finally, we have developed a theoretical model to predict the CF tensile strength and Young’s modulusbased on Griffith’s fracture theory and uniform stress model, and it was verified with a relative errorbetween the calculated and measured values less than 10%.