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Frequency Hopping Spread Spectrum Security Improvement with Encrypted Spreading Codes in a Partial Band Noise Jamming Environment

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Journal of Information Security 2013年第1期4卷 1-6页

作者： Amirhossein Ebrahimzadeh Abolfazl Falahati Digital Cryptography and Coding laboratory (dccs Lab) Department of Electrical Engineering Iran University of Science and Technology Tehran Iran

Frequency Hopping Spread Spectrum (FHSS) system is often deployed to protect wireless communication from jamming or to preclude undesired reception of the signal. Such themes can only be achieved if the jammer or undesired receiver does not have the knowledge of the spreading code. For this reason, unencrypted M-sequences are a deficient choice for the spreading code when a high level of security is required. The primary objective of this paper is to analyze vulnerability of linear feedback shift register (LFSRs) codes. Then, a new method based on encryption algorithm applied over spreading codes, named hidden frequency hopping is proposed to improve the security of FHSS. The proposed encryption security algorithm is highly reliable, and can be applied to all existing data communication systems based on spread spectrum techniques. Since the multi-user detection is an inherent characteristic for FHSS, the multi-user interference must be studied carefully. Hence, a new method called optimum pair “key-input” selection is proposed which reduces interference below the desired constant threshold.

关键词： Frequency Hopping Spread Spectrum Key Distribution Centre Key Encryption Key Linear Feedback Shift Register Frequency Hopping Code Division Multiple Access Direct Sequence Spread Spectrum

Transmission over Cognitive Radio Channel with Novel Secure LT Code

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Communications and Network 2013年第3期5卷 198-203页

作者： Elham Hosseini Abolfazl Falahati Department of Electrical Engineering (dccs Lab) Iran University of Science and Technology Tehran Iran

With the increasing of communication applications in recent years, the demand for radio spectral resources has increased significantly. Cognitive radio scenario was proposed to improve spectrum efficiency in wireless communication systems. In cognitive radio network, it is essential that control information is sent securely and reliably. Ensuring the trustworthiness of the transmitting of spectrum sensing information is important in the CR networks since spectrum sensing directly affects spectrum management and incumbent coexistence. In this paper, the first secondary link channel model is presented, then a secure LT Code is proposed to be compatible with presented channel model and acquires good QoS. As we may know, LT code overcomes packet loss when the channel of the SU is reclaimed by PU. In the new proposed combined encoding and ciphered block, a LT code matrix is used to generate a symmetric cryptographic key. Thus, less complexity observed in the processing computation. Besides, cryptographic key is not sent over the channel. As a result, an attacker has no way to eavesdrop the key unless he is prepared to consider all possible key combinations. This replaced block supplies secure controlling channel and increases spectrum efficiency too.

关键词： Cognitive Radio Symmetric Cryptographic Key Generation LT Code

Employing Power Allocation to Enhance Zero Forcing Scheme Advantages over Multi-Antenna Multiple Relay Networks

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International Journal of Communications, Network and System Sciences 2012年第11期5卷 736-742页

作者： Abolfazl Falahati Y. Attar Izi Department of Electrical Engineering (dccs Lab) Iran University of Science and Technology Tehran Iran

A multi-antenna multiple relay (MAMR) network is considered and a variation of two-hop zero-forcing amplify-forward relaying method is proposed. Deploying ZF method together with application of diagonal power allocation matrices at the relays, it is shown that the overall MAMR network is simplified to M independent single antenna multiple relay (SAMR) networks, where M is the number of source and destination antennas. This enables to incorporate network beamforming proposed for SAMR networks. Accordingly, using the BER as the performance metric, we present simulation results to show the proposed approach outperforms the common ZF method addressed in the literature.

关键词： Cooperative Communication MIMO Multiple Antennas Multiple Relay (MAMR) Networks Zero Forcing Power Allocation

dccs:A General-Purpose Distributed Cryptographic Computing System

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Wuhan University Journal of Natural Sciences 2007年第1期12卷 46-50页

作者： JIANG Zhonghua LIN Dongdai XU Lin LIN Lei State Key laboratory of Information Security Institute ofSoftware Chinese Academy of Sciences Beijing 100080 China Graduate School of the Chinese Academy of Sciences Beijing 100049 China

Distributed cryptographic computing system plays an important role since cryptographic computing is extremely computation sensitive. However, no general cryptographic computing system is available. Grid technology can give an efficient computational support for cryptographic applications. Therefore, a general-purpose grid-based distributed computing system called dccs is put forward in this paper. The architecture of dccs is simply described at first. The policy of task division adapted in dccs is then presented. The method to manage subtask is further discussed in detail. Furthermore, the building and execution process of a computing job is revealed. Finally, the details of dccs implementation under Globus Toolkit 4 are illustrated.

关键词： cryptography distributed computing execution plan computational grid

Deep Convective Clouds over the Northern Pacific and Their Relationship with Oceanic Cyclones

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Advances in Atmospheric Sciences 2015年第6期32卷 821-830页

作者： YI Mingjian FU Yunfei LIU Peng ZHENG Zhixia University of Science and Technology of China Anhui Provincial Academy of Environmental Sciences State Key laboratory of Severe Weather Chinese Academy of Meteorological Sciences

Based on combined CloudSat/CALIPSO detections, the seasonal occurrence of deep convective clouds （dccs） over the midlatitude North Pacific （NP） and cyclonic activity in winter were compared. In winter, dccs are more frequent over the central NP, from approximately 30~N to 45~N, than over other regions. The high frequencies are roughly equal to those occurring in this region in summer. Most of these dccs have cloud tops above a 12 km altitude, and the highest top is approximately 15 km. These wintertime marine dccs commonly occur during surface circulation conditions of low pressure, high temperature, strong meridional wind, and high relative humidity. Further, the maximum probability of dccs, according to the high correlation coefficient, was found in the region 10^-20~ east and 5^-10~ south of the center of the cyclones. The potential relationship between dccs and cyclones regarding their relative locations and circulation conditions was also identified by a case study. Deep clouds were generated in the warm conveyor belt by strong updrafts from baroclinic flows. The updrafts intensified when latent heat was released during the adjustment of the cyclone circulation current. This indicates that the dynamics of cyclones are the primary energy source for dccs over the NP in winter.

关键词： CloudSat deep convective clouds marine cyclones northern Pacific

The behavior of deep convective clouds over the warm pool and connection to the Walker circulation

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Science China Earth Sciences 2018年第11期61卷 1605-1621页

作者： Wenjing SHI Ziniu XIAO Yufei AI Beijing Institute of Applied Meteorology Beijing 100029 China Beijing Goldwind Science & Creation Windpower Equipment Co. Ltd. Xinjiang Goldwind Science & Technology Co. Ltd. Beijing 100176 China State Key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China laboratory for Climate and Ocean-Atmosphere Studies Department of Atmospheric and Oceanic Sciences School of Physics Peking University Beijing 100871 China

As the deep convective clouds(dccs) over the western Pacific and Indian Ocean warm pool may play different roles in the climate system, variations in DCC properties over these two sectors are investigated and compared. The DCC intensity and area varies more significantly in the Indian Ocean than the western Pacific sector, while the DCC frequency is comparable in both sectors at the seasonal scale. Although the Indian Ocean sector is strongly dominated by the seasonal evolution, the interannual variations in the two sectors are comparable for all three DCC properties(frequency, intensity, and area). Besides,Walker circulation is closely correlated with the interannual variability of dccs in both sectors. The Walker circulation strengthens(weakens) as the dccs shift eastward(westward) over the Indian Ocean sector and westward(eastward) over the western Pacific sector. When more or stronger dccs occur over the Indian Ocean sector(western Pacific sector), the Walker circulation becomes stronger(weaker) and shifts westward(eastward). Interestingly, the response of the Walker circulation to DCC variability over the warm pool is asymmetry. The asymmetry response of the Walker circulation to the negative and positive DCC anomaly may be related to the non-linearity internal variability of the atmosphere. dccs over the Indian Ocean sector have a much weaker nonlinear correlation with the Walker circulation than dccs over the western Pacific sector.

关键词： Satellite data Deep convective clouds Asymmetry response Walker circulation

Seasonal and Diurnal Variations of Cloud Systems over the Eastern Tibetan Plateau and East China:A Cloud-resolving Model Study

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Advances in Atmospheric Sciences 2022年第7期39卷 1034-1049页

作者： Jinghua CHEN Xiaoqing WU Chunsong LU Yan YIN Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044China Key laboratory of Meteorology and Ecological Environment of Hebei Province Shijiazhuang 050022China Department of Geological and Atmospheric Sciences Iowa State UniversityAmesIowa 50011USA

The seasonal and diurnal variations of cloud systems are profoundly affected by the large-scale and local *** this study,a one-year-long simulation was conducted using a two-dimensional cloud-resolving model over the Eastern Tibetan Plateau(ETP)and two subregions of Eastern China:Southern East China and Central East *** convective clouds(dccs)rarely occur in the cold season over ETP,whereas dccs appear in Eastern China throughout the year,and the ETP dccs are approximately 20%−30%shallower than those over Eastern *** strong rainfall events(precipitation intensity,PI>2.5 mm h−1)in Eastern China are related to warm-season dccs with ice cloud *** of the high elevation of the ETP,the warm-season freezing level is lower than in Eastern China,providing favorable conditions for ice cloud *** are responsible for the diurnal variations of warm-season rainfall in all three ***-season dccs over the ETP have the greatest total cloud water content and frequency in the afternoon,resulting in an afternoon rainfall *** addition,rainfall events in the ETP also exhibit a nocturnal peak in spring,summer,and autumn due to *** surface heat fluxes around noon can trigger or promote dccs in spring,summer,and autumn over the ETP but produce only cumulus clouds in winter due to the cold and dry environment.

关键词： the Tibetan Plateau convective system seasonal variation diurnal variation

Preliminary evidence for the presence of multiple forms of cell death in diabetes cardiomyopathy

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Acta Pharmaceutica Sinica B 2022年第1期12卷 1-17页

作者： Jinjing Wei Yongting Zhao Haihai Liang Weijie Du Lihong Wang Department of Endocrinology the First Affiliated Hospital of Jinan UniversityGuangzhou 510630China Department of Endocrinology the Second Affiliated Hospital of Harbin Medical UniversityHarbin 150081China Department of Pharmacology(State-Province Key Laboratories of Biomedicine-Pharmaceutics of China Key Laboratory of Cardiovascular ResearchMinistry of Education)College of PharmacyHarbin Medical UniversityHarbin 150081China

Diabetic mellitus(DM) is a common degenerative chronic metabolic disease often accompanied by severe cardiovascular complications(dccs) as major causes of death in diabetic patients with diabetic cardiomyopathy(DCM) as the most common DCC. The metabolic disturbance in DCM generates the conditions/substrates and inducers/triggers and activates the signaling molecules and death executioners leading to cardiomyocyte death which accelerates the development of DCM and the degeneration of DCM to heart *** forms of programmed active cell death including apoptosis, pyroptosis, autophagic cell death, autosis,necroptosis, ferroptosis and entosis have been identified and characterized in many types of cardiac *** has also been obtained for the presence of multiple forms of cell death in DCM. Most importantly,published animal experiments have demonstrated that suppression of cardiomyocyte death of any forms yields tremendous protective effects on DCM. Herein, we provide the most updated data on the subject of cell death in DCM, critical analysis of published results focusing on the pathophysiological roles of cell death, and pertinent perspectives of future studies.

关键词： Diabetes mellitus Diabetic cardiomyopathy Cell death Apoptosis Autophagic cell death Aautosis Pyroptosis Necroptosis Ferroptosis