基于LUT全更新的无模型预测电流控制方法

传统的模型预测控制(MPC)是一种高度依赖于系统参数的控制方法,参数失配会降低其电流控制效果。针对此问题,此处提出了一种基于查找表(LUT)的三相逆变器无模型预测电流控制(MFPCC)方法,仅使用不同时刻采样电流的测量数据,不依赖系统的模型信息,从而减小参数不确定性的影响。该方法将每个电压矢量作用于一个周期引起的不同电流梯度存储于表中,用于电流估计和预测,通过表的全更新避免表中数据的更新停滞带来的影响。构建虚拟矢量,增加有效矢量控制集,有效降低了电流总谐波畸变率(THD)。实验结果验证了所提方法的有效性。该方法促进了新能源的利用以及电能质量的改进。

Optically Stimulated Luminescence Dating of Sediments from the Pearl River Delta, Southeast China

The PRD （Pearl River Delta） was subjected to two transgressions respectively in the latest Pleistocene and Holocene. Position of coastal line of the latest Pleistocene transgression in some localities, especially at the center part of PRD is still uncertain. Thus quaternary sandy sediments in the central PRD are dated by OSL Optically Stimulated Luminescence） for determining the ancient coastal line. Samples are from Xiaohushan Hill at the center of PRD, where quaternary sediments deposited on a wave-cut platlbrm consist of two kinds of sediments： marine muddy-silt on the top and alluvial fine-sand in the lower part. The former is dated at 5.0-5.5 ka, which defines the time of Holocene transgression in the PRD. The alluvial fine-sand in the part is dated at 22-26 ka. For the alluvial fine-sand rests directly on a wave-cut platform, thus this wave-cut platform should have been existed before deposit of alluvial sand, i.e., formed during an earlier marine transgression that may have culminated in the sea level high at about 40 ka. The optically stimulated luminescence results are consistent with geological observations and compatible with TL （thermoluminescence） and ^14C ages from the same layers at other localities of the PRD.

Secure and efficient multi-message and multi-receiver ID-based signcryption for rekeying in ad hoc networks

In this paper, the security technology of ad hoc networks is studied.To improve the previous multi-receiver signcryption schemes, an ID-based multi-message and multi-receiver signcryption scheme for rekeying in ad hoc networks is proposed.In this scheme, a sender can simultaneously signcrypt n messeges for n receivers, and a receiver can unsigncrypt the ciphertext to get his message with his own private key.An analysis of this scheme indicates that it achieves authenticity and confidentiality in the random oracle model while being of lower computation and communication overhead.Finally, for the application of our scheme in ad hoc, a threshold key updating protocol for ad hoc networks is given.

Attribute Based DRM Scheme with Dynamic Usage Control in Cloud Computing

In order to achieve fine-grained access control in cloud computing,existing digital rights management(DRM) schemes adopt attribute-based encryption as the main encryption primitive.However,these schemes suffer from inefficiency and cannot support dynamic updating of usage rights stored in the cloud.In this paper,we propose a novel DRM scheme with secure key management and dynamic usage control in cloud computing.We present a secure key management mechanism based on attribute-based encryption and proxy re-encryption.Only the users whose attributes satisfy the access policy of the encrypted content and who have effective usage rights can be able to recover the content encryption key and further decrypt the content.The attribute based mechanism allows the content provider to selectively provide fine-grained access control of contents among a set of users,and also enables the license server to implement immediate attribute and user revocation.Moreover,our scheme supports privacy-preserving dynamic usage control based on additive homomorphic encryption,which allows the license server in the cloud to update the users' usage rights dynamically without disclosing the plaintext.Extensive analytical results indicate that our proposed scheme is secure and efficient.

Late Pleistocene-Holocene slip history of the Langshan-Seertengshan piedmont fault(Inner Mongolia,northern China) from cosmogenic ^(10)Be dating on a bedrock fault scarp

Offset geomorphic features and deformed late Quaternary strata indicate active deformation along the Langshan-Seertengshan piedmont fault （LSPF）, one of the most active faults in the Hetao fault zone in Inner Mongolia, North China. The widespread occurrence of bedrock fault scarps along the LSPF offers excellent opportunity to examine the faulting history. Using cosmogenic ^10Be exposure dating, we measured the exposure ages of the western Langshankou scarp, located in the middle segment of the LSPF. Our data revealed at least two earthquakes that occurred at 22.2±3.3 Ira and 7.2±2.4 ka, respectively. These events are consistent with previous paleoseismic trench studies. The regression of the relationship between the age and sampling height along the scarp yield a fault slip rate of 0.10 ±0.05/-0.06 mm/yr, which is significantly lower than the average post-late Pleistocene fault slip rate of ~1 mm/yr, as estimated from the offset of the T2 terraces by previous studies. This indicates that the slip of the LSPF may have been accommodated by other fault branches.

论起算点更新方法对城市轨道交通基础控制网成果的影响

基于统一限差法判定宁波市城市轨道交通首级控制网(简称框架网)点的稳定性,并利用原成果重新对基础控制网历期复测数据进行平差。对比结果表明,相比统一限差法,框架网采用全更新法会给下一级基础控制网点位成果带来平均约0.7 cm的影响,随后随着时间推移,影响程度扩散到大部分点位中,最大值在1.5 cm以内,满足目前基础控制网更新方案的要求。对采用全更新法后的起算点进行平差,基础控制网能有更好的精度,起算点与基础控制网点之间兼容性更好。

Investigation of Terraces along the Luoyunshan Piedmont Fault Zone and Its Tectonic Implications

Located at the west of the Linfen basin, the Luoyunshan piedmont fault zone controls the western boundary of the basin. According to the measurements of the terraces in eight gullies along the Luoyunshan fault zone, five levels of terraces, namely T1～T5 have developed in these gullies. The heights of terraces T1, T2, T3, T4 and T5 are about 3m, 8～10m, about 20m, about 30m and 40～50m, respectively. The dating data of the terraces and investigation of the faulted landforms show that the Luoyunshan fault zone has experienced much activity since the Late Quaternary. The uplift rate of the terraces was 0.41mm/a since the Middle-Late Pleistocene, and 0.75mm/a since the Holocene. The increasing trend of uplift rate of the terraces along the Luoyunshan fault zone from the Middle-Late Pleistocene to Holocene indicates the tendency of gradual tectonic uplift of the fault zone since the late Quaternary. This is in good agreement with the increasing trend of subsidence rate of the Linfen basin from the Late Pleistocene to Holocene.

Pseudo-Location Updating System for Privacy-Preserving Location-Based Services

With the rapid development of location-aware devices such as smart phones,Location-Based Services(LBSs) are becoming increasingly popular. Users can enjoy convenience by sending queries to LBS servers and obtaining service information that is nearby.However, these queries may leak the users' locations and interests to the un-trusted LBS servers, leading to serious privacy concerns. In this paper, we propose a Privacy-Preserving Pseudo-Location Updating System(3PLUS) to achieve k-anonymity for mobile users using LBSs. In 3PLUS, without relying on a third party, each user keeps pseudo-locations obtained from both the history locations and the encountered users, and randomly exchanges one of them with others when encounters occur. As a result, each user's buffer is disordered. A user can obtain any k locations from the buffer to achieve k-anonymity locally. The security analysis shows the security properties and our evaluation results indicate that the user's privacy is significantly improved.

Zooarchaeological perspective on the Broad Spectrum Revolution in the Pleistocene-Holocene transitional period,with evidence from Shuidonggou Locality 12,China

Based on optimal foraging theory,prey animals from the Shuidonggou Locality 12(SDG12) are divided into three types according to body size and defense traits:high-ranked large game,low-ranked slow small game,and low-ranked fast small game.Application of the Reciprocal of Simpson's Index to the three types of animals from SDG12 yields a relatively high level of evenness,which implies a broader meat diet of the SDG12 hominids.Compared to values of taxonomic evenness from Mediterranean sites,it is suggested that this dietary expansion probably resulted from the occurrence of the Broad Spectrum Revolution rather than from climatic changes in the Shuidonggou area.Comparative studies between the Natufian phases in Hayonim Cave and the SDG12 validate this argument.