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Sensor data compression based on MapReduce

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The Journal of China Universities of Posts and Telecommunications 2014年第1期21卷 60-66页

作者： YU Yu GUO Zhong-wen department of Computer science and Engineer Ocean University of China

A compression algorithm is proposed in this paper for reducing the size of sensor data. By using a dictionary-based lossless compression algorithm, sensor data can be compressed efficiently and interpreted without decompressing. The correlation between redundancy of sensor data and compression ratio is explored. Further, a parallel compression algorithm based on MapReduce [1] is proposed. Meanwhile, data partitioner which plays an important role in performance of MapReduce application is discussed along with performance evaluation criteria proposed in this paper. Experiments demonstrate that random sampler is suitable for highly redundant sensor data and the proposed compression algorithms can compress those highly redundant sensor data efficiently.

关键词： data compression sensor data MapReduce surveillance application measurement system

Ferulic acid alleviates long-term avermectin-induced damage to the spleen of carp and restores its inflammatory response and oxidative balance

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Journal of Environmental sciences 2025年第5期151卷 616-626页

作者： Hanyu Wang Shenye Feng Enzhuang Pan Xiaomeng Ji Mengyuan Zhou Shuai Zhang Baoshi Xu Huimiao Feng Jilei Yin Zibo Dong Jiangsu Key Laboratory of Marine Bioresources and Environment Co-Innovation Center of Jiangsu Marine Bio-industry TechnologyJiangsu Marine Pharmaceutical Resources Development Engineering Research CenterJiangsu Key Laboratory of Marine Pharmaceutical Compound ScreeningCollege of PharmacyJiangsu Ocean UniversityLianyungang 222005China department of Traditional Chinese Medicine Jiangsu Union Technical Institute Lianyungang Branch institute of Traditional Chinese MedicineLianyungang 222006China

Extensive use of avermectin(AVM)in agriculture can seriously contaminate fish in *** acid(FA)is a strong antioxidant sourced from plants and is widely applied in food and medicine,but its protective function on the immunological damage caused by AVM is still *** this study,carp were chronically exposed to(1/1096 hr LC_(50))AVM for 30 day(s),with a dietary supplement of FA(400 mg/kg)to assess its effects on carp *** experimental groups(n=10)included:control,AVM-exposed(2.404μg/L),FA+AVM co-treated,and FA ***-term AVM exposure altered spleen tissue,reducing serum complement C3(p<0.01)and immunoglobulin M levels(p<0.001),and increasing proinflammatory tnf-α(p<0.001),il-6(p<0.001),il-1β(p<0.001),and inos mRNA levels,whilst down-regulating the anti-inflammatory tgf-β(p<0.05).Additionally,it disrupted the balance of oxidative stress indicators such asMDA(p<0.001),T-AOC,GSH,and CAT,leading to spleen tissue apoptosis(42.4%).However,the addition of FA reversed these conditions,elevated the anti-inflammatory factor,and improved spleen immune function following chronic exposure to AVMin ***,the ability to restore oxidative homeostasis in carp by adjusting the Nrf2/NQO-1 axis protected the health of spleen *** discovery also supports the development of fish feed for aquaculture.

关键词： Avermectin Ferulic acid Oxidative stress Inflammation response

Lifetime Prolonging Algorithms for Underwater Sensor Networks

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China ocean Engineering 2006年第2期20卷 325-334页

作者：郭忠文李之伟于磊 College of Information science and Engineering Ocean University of China department of oceanography Ocean University of China

Underwater acoustic modem technology has attained a level of maturity to support underwater acoustic sensor networks （UASNs） which are generally formed by acoustically connected sensor nodes and a surface station providing a link to an on-shore control center. While many applications require long-term monitoring of the deployment area, the batterypowered network nodes limit the lifetime of UASNs. Therefore, designing a UASN that minimizes the power consumption while maximizing lifetime becomes a very difficult task. In this paper, a method is proposed to determine the optimum number of clnstens throngh combining an application-specific protocol architecture and underwater acoustic communication model so as to reduce the energy dissipation of UASNs. Deploying more sensor nodes which work alternately is another way to prolong the lifetime of UASNs, An algorithm is presented for selecting sensor nodes and putting them into operation in each round, ensuring the monitoring to the whole given area. The present results show that the algorithm can help prolong system lifetime remarkably when it is applied to other conventional approaches for sensor networks under the condition that the sensor node density is high.

关键词： lifetime acoustic networks underwater sensor networks telemetry

Study of scattering from time-varying Gerstners sea surface using second-order small slope approximation

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Chinese Physics B 2010年第5期19卷 260-268页

作者：张彦敏王运华郭立新 department of Physics Ocean University of China ocean Remote Sensing Key Laboratory of Ministry of Education Ocean University of China School of science Xidian University

Backscattered fields from one-dimensional time-varying Gerstners sea surface are calculated utilising the secondorder small slope approximation. It is well known that spectral properties of the backscattered echoes relate to the velocity of the small elementary scatterers on sea surface profiles. Therefore, modeling Doppler spectra from the ocean requires an accurate description of the sea surface motion. The profile of nonlinear Gerstners sea surface shows verticalskewness of sea waves, it is sharper at the crest and flatter at the trough than linear waves, and its maximum slope position is closer to the crest than to the trough. Furthermore, the horizontal component of the small elementary scatterers orbit velocity on the sea surface, which yields noticeable influence on Doppler spectra, can be obtained conveniently by Gerstners sea surface model. In this study the characteristics of Doppler spectra of backscattered fields from time-varying Gerstners sea surface are investigated and the dependences of the Doppler frequency and the Doppler bandwidth on the parameters, such as the wind speed, the radar frequency, the incident angle, etc. are discussed. It is shown that the Doppler bandwidth of microwave scattered fields from Gerstners sea surface is considerably broadened. For the case of high frequency backscattered fields, the values of the higher-order spectrum peaks are larger than those obtained by linear sea surface.

关键词： Gerstners sea surface electromagnetic scattering Doppler spectra second-order small slope approximation

Quantitative nanoscale mapping of three-phase thermal conductivities in filled skutterudites via scanning thermal microscopy

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National science Review 2018年第1期5卷 59-69页

作者： Ehsan Nasr Esfahani Feiyue Ma Shanyu Wang Yun Ou Jihui Yang Jiangyu Li department of Mechanical Engineering University of Washington Shenzhen Key Laboratory of Nanobiomechanics Shenzhen Institutes of Advanced TechnologyChinese Academy of Sciences department of Materials science andengineering University of Washington

In the last two decades, a nano structuring paradigm has been successfully applied in a wide range of thermoelectric materials, resulting in significant reduction in thermal conductivity and superior thermoelectric performance. These advances, however, have been accomplished without directly investigating the local thermoelectric properties, even though local electric current can be mapped with high spatial resolution. In fact, there still lacks an effective method that links the macroscopic thermoelectric performance to the local micro structures and properties. Here, we show that local thermal conductivity can be mapped quantitatively with good accuracy, nanometer resolution and one-to-one correspondence to the micro structure using a three-phase skutterudite as a model system. Scanning thermal microscopy combined with finite element simulations demonstrate close correlation between sample conductivity and probe resistance,enabling us to distinguish thermal conductivities spanning orders of magnitude, yet resolving thermal variation across a phase interface with small contrast. The technique thus provides a powerful tool to correlate local thermal conductivities, micro structures and macroscopic properties for nano structured materials in general and nano structured thermo electrics in particular.

关键词： thermal conductivity scanning thermal microscopy thermoelectric materials nanoscale heat transfer thermal imaging

Fe3O4 Octahedral Colloidal Crystals

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Nano Research 2011年第4期4卷 370-375页

作者： L-r Meng Weimeng Chen Yiwei Tan Lin Zou Chinping Chen Heping Zhou Qing Peng Yadong Li State Key Laboratory of New Ceramics and Fine Processing Department of Chemistry and Department of Materials Science andEngineering Tsinghua University Beijing 100084 China department of Physics Peking University Beijing 100871 China

We present a facile and controllable method for the large-scale fabrication of highly-ordered octahedral Fe3O4 colloidal ＂single crystals＂ without the assistance of a substrate. Oleic acid is used to reduce the solubility of the nano-building blocks in colloidal solution and to induce a ＂crystallization＂ process. Our colloidal crystals are of multimicron size and show typical crystallographic characteristics. They have a very robust structure and can serve as a novel ordered magnetic mesoporous material with a relatively narrow pore size distribution. The sample possesses an extremely high Verwey transition temperature （Tv） of 100 K and a high saturation magnetization （Ms） of 86 emu/g at 5 K based on its good crystallinity, as well as the interparticle dipolar interaction behavior arising from its unique structure. Electrochemical measurements have demonstrated the excellent capacity of the mesoporous colloidal crystals when used in lithium-ion batteries.

关键词： Fe3O4 self-assembly superlattice magnetic mesoporous material electrode material Verwey transition

A secure threshold Paillier proxy signature scheme

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Journal of Zhejiang University-science C(Computers and Electronics) 2010年第3期11卷 206-213页

作者： Pei-yih TING Chia-huei HSEU department of Computer science and Engineering National Taiwan Ocean University

As e-commerce applications and the underlying public key infrastructure have become more popular over time,many digital mechanisms emulating traditional business activities have been developed and deployed. To build a full-fledgedsecure digital world,secure implementations of more commercial activity primitives are required. In this paper,we present asecure proxy signature scheme and its threshold version based on the homomorphic Paillier cryptosystem,which can be used inmany e-commerce applications such as e-voting,e-bidding/auction,and privacy-preserving data mining. These two schemes areexistentially unforgeable against chosen-message attacks and chosen-warrant attacks in the random oracle model. Although it isbased on factoring,the threshold Paillier proxy scheme operates without requiring any trusted dealer or combiner. Thus,these twoschemes are practical for integration in modularized secure multi-party protocols.

关键词： Paillier proxy signature Threshold scheme Secure multi-party protocols Cryptographic primitives

Maneuvering Modeling and Simulation of AUV Dynamic Systems with Euler-Rodriguez Quaternion Method

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China ocean Engineering 2013年第3期27卷 403-416页

作者： C.W.Chen J.S.Kouh J.F.Tsai department of science Engineering and ocean Engineering National Taiwan University

The purpose of this study is to develop maneuvering models and systems of a simulator to improve the motion performance of autonomous underwater vehicles （AUVs） at the preliminary design stages in advance. The AUVs simulation systems based on the standard submarine equations of motion in six-degree-of-freedom （6-DOF） integrated with the Euler-Rodriguez quaternion method for representing singularity-free AUV attitude and time-saving calculation, and with a nonlinear control model for maneuvering and depth control simulations, time-marching in the fourth-order Runge-Kutta scheme. For validation of the simulation codes, results of the ISiMI AUV open-loop tests including turning test and zigzag test as well as an AUV simulator on the basis of Euler-angle method were used to compare with the quaternion-based AUV simulator. The computational results from the proposed simulator agree well with those from both the ISiMI AUV experiments and the Euler-angle based simulations. Additionally, a new maneuvering procedure, namely ＂put-out＂ was implemented to test directional stability for a large-scale AUV in the proposed AUV simulator that can be considered for vehicles in space as well as in constrained planes.

关键词： autonomous underwater vehicle (.4 UV) Euler-Rodriguez quaternion hydrodynamics maneuvering systemdynamics

ENSO-induced Latitudinal Variation of the Subtropical Jet Modulates Extreme Winter Precipitation over the Western Himalaya

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Advances in Atmospheric sciences 2025年第3期 427-437页

作者： Priya BHARATI Pranab DEB Kieran M.R.HUNT Andrew ORR Mihir Kumar DASH Centre for ocean River Atmosphere and Land Sciences (CORAL) Indian Institute of Technology Kharagpur department of Meteorology University of Reading National Centre for Atmospheric science University of Reading British Antarctic Survey

In this study, we investigate the complex relationship between western disturbances(WDs), the El Ni?o–Southern Oscillation(ENSO), and extreme precipitation events(EPEs) in the western Himalaya(WH) during the extended winter season(November–March). WDs west of WH coincide with 97% of recorded EPEs, contributing substantially(32% in winter, 11% annually) to total precipitation within WH. WDs are 6% less frequent and 4% more intense during El Ni?o than La Ni?a to the west of WH. During El Ni?o(compared to La Ni?a) years, WDs co-occurring with EPEs are significantly more intense and associated with 17% higher moisture transport over “WH box”(the selected region where most of the winter precipitation over WH occurs). This results in twice the EPE frequency during El Ni?o periods than La Ni?a periods. A substantial southward shift(～180 km) of the subtropical jet(STJ) axis during El Ni?o brings WD tracks further south towards their primary moisture sources, especially the Arabian Sea. We have shown that WDs that are both more intense and pass to the south of their typical latitudes have higher levels of vertically integrated moisture flux(VIMF)within them. VIMF convergence in the most intense pentile of WDs is 5.7 times higher than in the weakest, and is 3.4 times higher in the second lowest latitude pentile than in the highest. Overall, this study demonstrates a direct link between changes in the latitudinal position and intensity of WDs associated with the winter STJ, and moisture convergence, which leads to the occurrence of EPEs over WH during ENSO phases.

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