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Efficient enhancing scheme for TCP performance over satellite-based internet

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Journal of Systems Engineering and Electronics 2007年第1期18卷 177-182页

作者： wang lina Gu Xuemai Information Engineering School Beijing Univ. of Science and Technology Beijing 100083 E R. China Communication Research Center Harbin Inst. of Technology Harbin 150001 P. R. China

Satellite link characteristics drastically degrade transport control protocol （TCP） performance. An efficient performance enhancing scheme is proposed. The improvement of TCP performance over satellite-based Interuet is accomplished by protocol transition gateways at each end of a satellite link. The protocol which runs over a satellite link executes the receiver-driven flow control and acknowledgements- and timeouts-based error control strategies. The validity of this TCP performance enhancing scheme is verified by a series of simulation experiments. Results show that the proposed scheme can efficiently enhance the TCP performance over satellite-based Internet and ensure that the available bandwidth resources of the satellite link are fully utilized.

关键词： Geostationary satellites Protocol transition gateway Transport control protocol

A Multi-Vehicle Cooperative Localization Method Based on Belief Propagation in Satellite Denied Environment

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Journal of Beijing Institute of Technology 2022年第5期31卷 464-472页

作者： Jiaqi wang lina wang School of Computer and Communication Engineering University of Science and Technology BeijingBeijing 100083China

The global navigation satellite system(GNSS)is currently being used extensively in the navigation system of ***,the GNSS signal will be faded or blocked in complex road environments,which will lead to a decrease in positioning *** to the higher-precision synchronization provided in the sixth generation(6G)network,the errors of ranging-based positioning technologies can be effectively *** the same time,the use of terahertz in 6G allows excellent resolution of range and angle,which offers unique opportunities for multi-vehicle cooperative localization in a GNSS denied *** paper introduces a multi-vehicle cooperative localization *** the proposed method,the location estimations of vehicles are derived by utilizing inertial measurement and then corrected by exchanging the beliefs with adjacent vehicles and roadside *** multi-vehicle cooperative localization problem is represented using a factor *** iterative algorithm based on belief propagation is applied to perform the inference over the factor *** results demonstrate that our proposed method can offer a considerable capability enhancement on localization accuracy.

关键词： cooperative localization belief propagation factor graph inertial navigation system internet of vehicles

Novel evaluation method of TCP performance over satellite links

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Journal of Systems Engineering and Electronics 2006年第2期17卷 462-466,F0003页

作者： wang lina Gu Xuemai Information Engineering School Univ. of Science and Technology Beijing Beijing 100083 P. R. China Communication Research Center Harbin Inst. of Technology Harbin 150001 P. R. China

A novel and efficient method to evaluate the transmission control protocol （TCP） performance over satellite links is presented. A TCP module is divided into three functional blocks, namely data processing, congestion control and error control The re-established TCP module is easy to update TCP congestion control strategy or error control strategy. With the proposed analysis approach, the interactions between different congestion control and error control mechanisms, as well as the performanee of various combination protocols in satellite environments have been investigated. Simulation results obtained through a series of experiments have shown that SNACK-based error control strategy can perform well with any other congestion control strategy. The best performanee can be achieved by TCP NewReno congestion control strategy and SNACK-based error control strategy.

关键词： geostationary satellites transmission control protocol congestion control error control.

Greenhouse microclimate environment adaptive control based on a wireless sensor network

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International Journal of Agricultural and Biological Engineering 2020年第3期13卷 64-69页

作者： lina wang Binrui wang College of Mechanical and Electronic Engineering China Jiliang UniversityHangzhou 310018China

Environmental parameter measurements from various sensors spatially distributed in greenhouse crops can be used to create an accurate and detailed depiction of the climate in different regions of the *** environments have an impact on crop yield,productivity,quantitative and qualitative characteristics of plants,and various plant *** this study,an automatic monitoring system based on a wireless sensor network was designed to monitor the survival rate of greenhouse *** system design includes a sensor model selection and placement process,host computer monitoring software and communication module *** Zigbee protocol was used for wireless communication between the *** proposed fuzzy-PID controller was easy to design and highly adaptive to the measurement errors of the *** test results show that the system valuable for monitoring the environment in the greenhouse,where it was successful in controlling and maintaining an optimal microclimate condition.

关键词： greenhouse microclimate control wireless sensor network fuzzy-PID control

Hot deformation behavior of EA4T steel

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Acta Metallurgica Sinica(English Letters) 2012年第5期25卷 374-382页

作者： Gang XU lina wang Shiqi LI Le wang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing100083 China

The compressive deformation behavior of EA4T steel was investigated at tempera- tures ranging from 950 to 1150℃ and strain rates from 0.1 to 20 s-1 on Gleeble-1500 thermo-simulation machine. The work hardening rate versus stress curves were used to determine the characteristic points of flow curves. The application of constitutive equations to determine the hot working constants of this material was discussed. Fur- thermore, the effect of Zener-Hollomon parameter （Z） on the characteristic points of flow curves was studied using the power law relation. The deformation activation energy of this steel was determined as 309.5 kJ/mol. Some behaviors were compared to other steels.

关键词： EA4T steel Constitutive equations Activation energy Workhardening rate

Process optimization study on the carbonylation of methyl acetate

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Chinese Journal of Chemical Engineering 2018年第9期26卷 1937-1942页

作者： Baohe wang Baomin Ge Jing Zhu lina wang Key Laboratory for Green Chemical Technology of Ministry of Education Research and Development Center of Petrochemical Technology Tianjin University

Acetic anhydride is the important organic chemical raw material, and is used widely in chemical industry,pharmaceutical industry, dyes, spices and other fields. In this paper, the process of carbonylation of methyl acetate in rhodium iodine catalyst system was studied, and the suitable reaction conditions were *** the same time, the kinetic model was established. The optimum reaction conditions were as follows： the reaction pressure was 5 MPa, the hydrogen content was 8%, the amount of iodomethane was 15%, the amount of lithium iodide was 3%, the reaction temperature was 150 ℃ and the reaction time is 3 h. Under the above reaction conditions, the selectivity of the reaction is close to 100% and the conversion is as high as 92%. The macroscopic kinetic model of the reaction was established in the temperature range of 120 ℃–150 ℃. The reaction is an irreversible reaction without the formation of by-products and the dynamic equation is also given in the Conclusions section.

关键词： Carbonylation Rhodium iodine catalyst Reaction conditions Kinetics

Spectroscopic characterization and photochemistry of the Criegee intermediate CF_(3)C(H)OO

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Journal of Environmental Sciences 2022年第4期34卷 160-169页

作者： lina wang Zhuang Wu Bo Lu Xiaoqing Zeng Department of Chemistry Shanghai Key Laboratory of Molecular Catalysts and Innovative MaterialsFudan UniversityShanghai 200433China

Criegee intermediates(CIs),also known as carbonyl oxide,are reactive intermediates that play an important role in the atmospheric *** on the structures and reactivity of CIs is of fundamental importance in understanding the underlying mechanism of their atmospheric *** sharp contrast to the intensively studied parent molecule(CH_(2)OO)and the alkyl-substituted derivatives,the knowledge about the fluorinated analogue CF_(3)C(H)OO is *** carefully heating the triplet carbene CF_(3)CH in an O2-doped Ar-matrix to 35 K,the elusive carbonyl oxide CF_(3)C(H)OO in syn-and anti-conformations has been generated and characterized with infrared(IR)and ultraviolet-visible(UV-vis)*** spectroscopic identification is supported by^(18)O-labeling experiments and quantum chemical calculations at the B3 LYP/6-311++G(3df,3pd)and MP2/6-311++G(2d,2p)*** the long-wavelength irradiation(λ>680 nm),both conformers of CF_(3)C(H)OO decompose to give trifluoroacetaldehyde CF_(3)C(H)O and simultaneously rearrange to the isomeric dioxirane,cyclic-CF_(3)CH(OO),which undergoes isomerization to the lowest-energy carboxylic acid CF_(3)C(O)OH upon UV-light excitation at 365 *** O_(2)-oxidation of CF_(3)CH via the intermediacy of CF_(3)C(H)OO and cyclic-CF_(3)CH(OO)might provide new insight into the mechanism for the degradation of hydro-chlorofluorocarbon CF_(3)CHCl_(2)(HCFC-123)in the atmosphere.

关键词： Criegee intermediates CF_(3)COOH(TFA) CF_(3)CHCl_(2)(HCFC-123) Photochemistry Matrix-isolation spectroscopy

Memway:In-Memory Waylaying Acceleration for Practical Rowhammer Attacks Against Binaries

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Tsinghua Science and Technology 2019年第5期24卷 535-545页

作者： Lai Xu Rongwei Yu lina wang Weijie Liu the Key Laboratory of Aerospace Information Security and Trusted Computing Ministry of Education School of Cyber Science and Engineering Wuhan University

The Rowhammer bug is a novel micro-architectural security threat, enabling powerful privilege-escalation attacks on various mainstream platforms. It works by actively flipping bits in Dynamic Random Access Memory(DRAM) cells with unprivileged instructions. In order to set up Rowhammer against binaries in the Linux page cache, the Waylaying algorithm has previously been proposed. The Waylaying method stealthily relocates binaries onto exploitable physical addresses without exhausting system memory. However, the proof-of-concept Waylaying algorithm can be easily detected during page cache eviction because of its high disk I/O overhead and long running time. This paper proposes the more advanced Memway algorithm, which improves on Waylaying in terms of both I/O overhead and speed. Running time and disk I/O overhead are reduced by 90% by utilizing Linux tmpfs and inmemory swapping to manage eviction files. Furthermore, by combining Memway with the unprivileged posix fadvise API, the binary relocation step is made 100 times faster. Equipped with our Memway+fadvise relocation scheme,we demonstrate practical Rowhammer attacks that take only 15–200 minutes to covertly relocate a victim binary,and less than 3 seconds to flip the target instruction bit.

关键词： Rowhammer bug Waylaying algorithm in-memory swapping page cache eviction

Orientation factor analysis of deformation mechanisms under special processing techniques in AZ31 magnesium alloys

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Acta Metallurgica Sinica(English Letters) 2010年第1期23卷 63-71页

作者： Ping YANG lina wang Xiao LI Li MENU School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Material Department School of Tianjin University of Science and Technology Beijing Tianjin 301830 China

Experiments show that special processing techniques such as asymmetrical rolling （ASR）, equal channel angular pressing （ECAP） and equal channel angular rolling （ECAR） can weaken the basal texture of the magnesium alloys and therefore improve their plasticity. However, the deformation mechanisms related are different. In this paper, we determine the deformation mechanisms activated during ASR, ECAP and ECAR by calculation of orientation factors. Analysis shows that during ASR the shear stress σ13 on the rolling plane of the samples obviously weakens the basal slip and tension twinning that all produce basal texture and improve plasticity due to the promotion of tilt basal texture. During ECAP the shear stress σs on the intersecting plane of two channels promotes tension twinning in the basal oriented grains, whereas under ECAR the shear stress σ13 induced by roller friction on the rolling plane produces the shear stress as on the intersection plane of the two channels that also promotes tension twinning. Although the shear strain is lower in ECAR than in ECAP, the channel clearance in ECAR facilitates tension twinning.

关键词： Magnesium Asymmetrical rolling Equal channel angular pressing Equal channel angular rolling Deformation