Many ＂rich - connected＂ topologies with multiple parallel paths between smwers have been proposed for data center networks recently to provide high bisection bandwidth, but it re mains challenging to fully utilize t...Many ＂rich - connected＂ topologies with multiple parallel paths between smwers have been proposed for data center networks recently to provide high bisection bandwidth, but it re mains challenging to fully utilize the high network capacity by appropriate multi- path routing algorithms. As flow-level path splitting may lead to trafl＇ic imbalance between paths due to flow- size difference, packet-level path splitting attracts more attention lately, which spreads packets from flows into multiple available paths and significantly improves link utilizations. However, it may cause packet reordering, confusing the TCP congestion control algorithm and lowering the throughput of flows. In this paper, we design a novel packetlevel multi-path routing scheme called SOPA, which leverag- es OpenFlow to perform packet-level path splitting in a round- robin fashion, and hence significantly mitigates the packet reordering problem and improves the network throughput. Moreover, SOPA leverages the topological feature of data center networks to encode a very small number of switches along the path into the packet header, resulting in very light overhead. Compared with random packet spraying （RPS）, Hedera and equal-cost multi-path routing （ECMP）, our simulations demonstrate that SOPA achieves 29.87%, 50.41% and 77.74% higher network throughput respectively under permutation workload, and reduces average data transfer completion time by 53.65%, 343.31% and 348.25% respectively under production workload.展开更多
Massive MIMO is one of tile enabling technologies tbr beyond 4G and 5G systems due to its ability to provide beamforming gain and reduce interference Dual-polarized antenna is widely adopted to accommodate a large num...Massive MIMO is one of tile enabling technologies tbr beyond 4G and 5G systems due to its ability to provide beamforming gain and reduce interference Dual-polarized antenna is widely adopted to accommodate a large number of antenna elements in limited space. However, current CSI（channel state information） feedback schemes developed in LTE for conventional MIMO systems are not efficient enough for massive MIMO systems since the overhead increases almost linearly with the number of antenna. Moreover, the codebook for massive MIMO will be huge and difficult to design with the LTE methodology. This paper proposes a novel CSI feedback scheme named layered Multi-paths Information based CSI Feedback （LMPIF）, which can achieve higher spectrum efficiency for dual-polarized antenna system with low feedback overhead. The MIMO channel is decomposed into long term components （multipath directions and amplitudes） and short term components （multipath phases）. The relationship between the two components and the optimal precoder is derived in closed form. To reduce the overhead, different granularities in feedback time have been applied for the long term components and short term components Link and system level simulation results prove that LMPIF can improve performance considerably with low CSI feedback overhead.展开更多
Gravel packing is a promising sand control method for natural gas wells in deepwater environments.However,premature screenout,wellbore shrinkage,and packer installationlimit gravel packing efficiency in long-reach hor...Gravel packing is a promising sand control method for natural gas wells in deepwater environments.However,premature screenout,wellbore shrinkage,and packer installationlimit gravel packing efficiency in long-reach horizontal wells.In this paper,we introduce a novel multi-path screen that provides alternative pathways once the circulating annulus is blocked.The basic geometric parameters of the screen are given first.Then,the frictional pressure loss in each circulating unit during packing is evaluated.Finally,the application of this screen in a long-reach horizontal well in the northern South China Sea is discussed.The application results demonstrate the applicability of multi-path screens in complex downhole completion conditions.The multi-path screen described here may widen the application ranges of gravel packing techniques to meet the exploitation demand for unconventional natural gas resources,such as marine natural gas hydrate.展开更多
This paper presents a vision-based navigation framework for micro air vehicles(MAVs)operating in confined warehouse environments.To address the trade-off between low localization accuracy in mapless methods and high c...This paper presents a vision-based navigation framework for micro air vehicles(MAVs)operating in confined warehouse environments.To address the trade-off between low localization accuracy in mapless methods and high computational demands in map-based approaches,the proposed system leverages topology-aware path guidance using monocular vision.Navigation is driven by a digital instruction format(DIF)that encodes both the path index and target junction,enabling autonomous navigation without environmental modifications.The framework comprises a cascaded perception-encoding-control pipeline.For structured paths,foreground pixel density trend analysis with sliding window smoothing for robust junction recognition,while lateral proportionalintegral-derivative(PID)control ensures accurate path tracking.For geometric trajectories,the control logic incorporates L-junction triggers,fixed-angle turns,and spatial yaw correction to accommodate sharp corners and curved segments.ROS-Gazebo simulations validate the method’s effectiveness,achieving up to 94.40%junction recognition accuracy(92.01%on average),trajectory tracking errors below 0.1 m,and terminal localization deviations under 0.2 m.These results validate the method’s accuracy,stability,and suitability for computationally constrained MAV platforms in warehouse automation.展开更多
With the continuous development of artificial intelligence and machine learning techniques,there have been effective methods supporting the work of dermatologist in the field of skin cancer detection.However,object si...With the continuous development of artificial intelligence and machine learning techniques,there have been effective methods supporting the work of dermatologist in the field of skin cancer detection.However,object significant challenges have been presented in accurately segmenting melanomas in dermoscopic images due to the objects that could interfere human observations,such as bubbles and scales.To address these challenges,we propose a dual U-Net network framework for skin melanoma segmentation.In our proposed architecture,we introduce several innovative components that aim to enhance the performance and capabilities of the traditional U-Net.First,we establish a novel framework that links two simplified U-Nets,enabling more comprehensive information exchange and feature integration throughout the network.Second,after cascading the second U-Net,we introduce a skip connection between the decoder and encoder networks,and incorporate a modified receptive field block(MRFB),which is designed to capture multi-scale spatial information.Third,to further enhance the feature representation capabilities,we add a multi-path convolution block attention module(MCBAM)to the first two layers of the first U-Net encoding,and integrate a new squeeze-and-excitation(SE)mechanism with residual connections in the second U-Net.To illustrate the performance of our proposed model,we conducted comprehensive experiments on widely recognized skin datasets.On the ISIC-2017 dataset,the IoU value of our proposed model increased from 0.6406 to 0.6819 and the Dice coefficient increased from 0.7625 to 0.8023.On the ISIC-2018 dataset,the IoU value of proposed model also improved from 0.7138 to 0.7709,while the Dice coefficient increased from 0.8285 to 0.8665.Furthermore,the generalization experiments conducted on the jaw cyst dataset from Quzhou People’s Hospital further verified the outstanding segmentation performance of the proposed model.These findings collectively affirm the potential of our approach as a valuable tool in supporting clinical decision-making in the field of skin cancer detection,as well as advancing research in medical image analysis.展开更多
The performance of multi-user code to direct spreading bi-phase shift keying （DS-BPSK） direct impulse ultra wideband （UWB） systems under indoor multi-user and multi-path environment is analyzed and simulated. The ...The performance of multi-user code to direct spreading bi-phase shift keying （DS-BPSK） direct impulse ultra wideband （UWB） systems under indoor multi-user and multi-path environment is analyzed and simulated. The system output signals with Rake receiver are derived, then a simple and practical code selection scheme is given; i. e., with a large occupation to empty ratio of the repeating pulses, directly choosing those random or pseudo-random user codes with enough length and good co-relative orthogonal features will make the performance of DS-BPSK approximate the optimum and, so there is no need to carefully design the code or its type. The system multi-access performances are simulated using Gold sequence and PN codes as multi-user codes under CMI-CM4 multi-path channels. Simulation results prove that the proposed scheme is feasible.展开更多
目的:探讨ACK1(活化的CDC42结合激酶)对肝细胞肝癌(HCC)增殖影响的分子机制。方法:用q RTPCR法和Western blotting法检测细胞中ACK1 m RNA和蛋白的表达。用ACK1 sh RNA p RS质粒转染细胞法构建基因敲除模型。用免疫印迹法来检验肝癌细胞...目的:探讨ACK1(活化的CDC42结合激酶)对肝细胞肝癌(HCC)增殖影响的分子机制。方法:用q RTPCR法和Western blotting法检测细胞中ACK1 m RNA和蛋白的表达。用ACK1 sh RNA p RS质粒转染细胞法构建基因敲除模型。用免疫印迹法来检验肝癌细胞中ACK1对p-ACK1、AKT、p-AKT、MMP2和MMP9的调节效应。用流式细胞仪,凋亡蛋白酶3/7活力测定仪,Brd U渗入法,MTT法,检测肝癌细胞的凋亡、增殖能力。结果:肝癌细胞株SMMC-7721,Huh-7,Hep G2,BEL-7402和MHCC-97H细胞ACK1 m RNA和蛋白的表达明显比正常肝细胞LO2中要高,差异有统计学意义(P均<0.01)。肝癌细胞MHCC-97H中沉默ACK1可使活化态的AKT(p-AKT)明显减少,而非活化态的AKT量变化不大,差异有统计学意义(P<0.01)。在研究中,我们发现沉默ACK1可引起肝癌细胞MHCC-97H中作为AKT信号通路下游的MMP2和MMP9表达下调,差异有统计学意义(P<0.01)。此外,沉默ACK1可促进肝癌细胞MHCC-97H凋亡并抑制其增殖能力,差异有统计学意义(P<0.01)。结论:在肝细胞肝癌中,过表达ACK1通过激活AKT信号通路来促进肝癌细胞的增殖。展开更多
基金supported by the National Basic Research Program of China(973 program)under Grant No.2014CB347800 and No.2012CB315803the National High-Tech R&D Program of China(863 program)under Grant No.2013AA013303+1 种基金the Natural Science Foundation of China under Grant No.61170291,No.61133006,and No.61161140454ZTE IndustryAcademia-Research Cooperation Funds
文摘Many ＂rich - connected＂ topologies with multiple parallel paths between smwers have been proposed for data center networks recently to provide high bisection bandwidth, but it re mains challenging to fully utilize the high network capacity by appropriate multi- path routing algorithms. As flow-level path splitting may lead to trafl＇ic imbalance between paths due to flow- size difference, packet-level path splitting attracts more attention lately, which spreads packets from flows into multiple available paths and significantly improves link utilizations. However, it may cause packet reordering, confusing the TCP congestion control algorithm and lowering the throughput of flows. In this paper, we design a novel packetlevel multi-path routing scheme called SOPA, which leverag- es OpenFlow to perform packet-level path splitting in a round- robin fashion, and hence significantly mitigates the packet reordering problem and improves the network throughput. Moreover, SOPA leverages the topological feature of data center networks to encode a very small number of switches along the path into the packet header, resulting in very light overhead. Compared with random packet spraying （RPS）, Hedera and equal-cost multi-path routing （ECMP）, our simulations demonstrate that SOPA achieves 29.87%, 50.41% and 77.74% higher network throughput respectively under permutation workload, and reduces average data transfer completion time by 53.65%, 343.31% and 348.25% respectively under production workload.
基金supported by the National High-Tech R&D Program(863 Program 2015AA01A705)
文摘Massive MIMO is one of tile enabling technologies tbr beyond 4G and 5G systems due to its ability to provide beamforming gain and reduce interference Dual-polarized antenna is widely adopted to accommodate a large number of antenna elements in limited space. However, current CSI（channel state information） feedback schemes developed in LTE for conventional MIMO systems are not efficient enough for massive MIMO systems since the overhead increases almost linearly with the number of antenna. Moreover, the codebook for massive MIMO will be huge and difficult to design with the LTE methodology. This paper proposes a novel CSI feedback scheme named layered Multi-paths Information based CSI Feedback （LMPIF）, which can achieve higher spectrum efficiency for dual-polarized antenna system with low feedback overhead. The MIMO channel is decomposed into long term components （multipath directions and amplitudes） and short term components （multipath phases）. The relationship between the two components and the optimal precoder is derived in closed form. To reduce the overhead, different granularities in feedback time have been applied for the long term components and short term components Link and system level simulation results prove that LMPIF can improve performance considerably with low CSI feedback overhead.
基金supported by the National Natural Science Foundation of China(Grant No.41976074)Key Laboratory of Gas Hydrate,Guangzhou Institute of Energy Conversion,Chinese Academy of Sciences(Grant No.E129kf1301).
文摘Gravel packing is a promising sand control method for natural gas wells in deepwater environments.However,premature screenout,wellbore shrinkage,and packer installationlimit gravel packing efficiency in long-reach horizontal wells.In this paper,we introduce a novel multi-path screen that provides alternative pathways once the circulating annulus is blocked.The basic geometric parameters of the screen are given first.Then,the frictional pressure loss in each circulating unit during packing is evaluated.Finally,the application of this screen in a long-reach horizontal well in the northern South China Sea is discussed.The application results demonstrate the applicability of multi-path screens in complex downhole completion conditions.The multi-path screen described here may widen the application ranges of gravel packing techniques to meet the exploitation demand for unconventional natural gas resources,such as marine natural gas hydrate.
基金supported by the Fundamental Research Grant Scheme(FRGS)(No.FRGS/1/2024/TK04/USM/02/3)funded by the Malaysian Ministry of Higher Education(MOHE).
文摘This paper presents a vision-based navigation framework for micro air vehicles(MAVs)operating in confined warehouse environments.To address the trade-off between low localization accuracy in mapless methods and high computational demands in map-based approaches,the proposed system leverages topology-aware path guidance using monocular vision.Navigation is driven by a digital instruction format(DIF)that encodes both the path index and target junction,enabling autonomous navigation without environmental modifications.The framework comprises a cascaded perception-encoding-control pipeline.For structured paths,foreground pixel density trend analysis with sliding window smoothing for robust junction recognition,while lateral proportionalintegral-derivative(PID)control ensures accurate path tracking.For geometric trajectories,the control logic incorporates L-junction triggers,fixed-angle turns,and spatial yaw correction to accommodate sharp corners and curved segments.ROS-Gazebo simulations validate the method’s effectiveness,achieving up to 94.40%junction recognition accuracy(92.01%on average),trajectory tracking errors below 0.1 m,and terminal localization deviations under 0.2 m.These results validate the method’s accuracy,stability,and suitability for computationally constrained MAV platforms in warehouse automation.
基金funded by Zhejiang Basic Public Welfare Research Project,grant number LZY24E060001supported by Guangzhou Development Zone Science and Technology(2021GH10,2020GH10,2023GH02)+1 种基金the University of Macao(MYRG2022-00271-FST)the Science and Technology Development Fund(FDCT)of Macao(0032/2022/A).
文摘With the continuous development of artificial intelligence and machine learning techniques,there have been effective methods supporting the work of dermatologist in the field of skin cancer detection.However,object significant challenges have been presented in accurately segmenting melanomas in dermoscopic images due to the objects that could interfere human observations,such as bubbles and scales.To address these challenges,we propose a dual U-Net network framework for skin melanoma segmentation.In our proposed architecture,we introduce several innovative components that aim to enhance the performance and capabilities of the traditional U-Net.First,we establish a novel framework that links two simplified U-Nets,enabling more comprehensive information exchange and feature integration throughout the network.Second,after cascading the second U-Net,we introduce a skip connection between the decoder and encoder networks,and incorporate a modified receptive field block(MRFB),which is designed to capture multi-scale spatial information.Third,to further enhance the feature representation capabilities,we add a multi-path convolution block attention module(MCBAM)to the first two layers of the first U-Net encoding,and integrate a new squeeze-and-excitation(SE)mechanism with residual connections in the second U-Net.To illustrate the performance of our proposed model,we conducted comprehensive experiments on widely recognized skin datasets.On the ISIC-2017 dataset,the IoU value of our proposed model increased from 0.6406 to 0.6819 and the Dice coefficient increased from 0.7625 to 0.8023.On the ISIC-2018 dataset,the IoU value of proposed model also improved from 0.7138 to 0.7709,while the Dice coefficient increased from 0.8285 to 0.8665.Furthermore,the generalization experiments conducted on the jaw cyst dataset from Quzhou People’s Hospital further verified the outstanding segmentation performance of the proposed model.These findings collectively affirm the potential of our approach as a valuable tool in supporting clinical decision-making in the field of skin cancer detection,as well as advancing research in medical image analysis.
文摘The performance of multi-user code to direct spreading bi-phase shift keying （DS-BPSK） direct impulse ultra wideband （UWB） systems under indoor multi-user and multi-path environment is analyzed and simulated. The system output signals with Rake receiver are derived, then a simple and practical code selection scheme is given; i. e., with a large occupation to empty ratio of the repeating pulses, directly choosing those random or pseudo-random user codes with enough length and good co-relative orthogonal features will make the performance of DS-BPSK approximate the optimum and, so there is no need to carefully design the code or its type. The system multi-access performances are simulated using Gold sequence and PN codes as multi-user codes under CMI-CM4 multi-path channels. Simulation results prove that the proposed scheme is feasible.
文摘目的:探讨ACK1(活化的CDC42结合激酶)对肝细胞肝癌(HCC)增殖影响的分子机制。方法:用q RTPCR法和Western blotting法检测细胞中ACK1 m RNA和蛋白的表达。用ACK1 sh RNA p RS质粒转染细胞法构建基因敲除模型。用免疫印迹法来检验肝癌细胞中ACK1对p-ACK1、AKT、p-AKT、MMP2和MMP9的调节效应。用流式细胞仪,凋亡蛋白酶3/7活力测定仪,Brd U渗入法,MTT法,检测肝癌细胞的凋亡、增殖能力。结果:肝癌细胞株SMMC-7721,Huh-7,Hep G2,BEL-7402和MHCC-97H细胞ACK1 m RNA和蛋白的表达明显比正常肝细胞LO2中要高,差异有统计学意义(P均<0.01)。肝癌细胞MHCC-97H中沉默ACK1可使活化态的AKT(p-AKT)明显减少,而非活化态的AKT量变化不大,差异有统计学意义(P<0.01)。在研究中,我们发现沉默ACK1可引起肝癌细胞MHCC-97H中作为AKT信号通路下游的MMP2和MMP9表达下调,差异有统计学意义(P<0.01)。此外,沉默ACK1可促进肝癌细胞MHCC-97H凋亡并抑制其增殖能力,差异有统计学意义(P<0.01)。结论:在肝细胞肝癌中,过表达ACK1通过激活AKT信号通路来促进肝癌细胞的增殖。
