光纤无线电系统中的新型探测法研究

光纤无线电系统利用光载波携带毫米波信号在中心站和基站之间构成上行和下行传输链路,能够满足宽带无线接入系统的需求.利用光外差的方法产生毫米波信号是光载毫米波最简单和直接的方式.分析了在光纤无线电系统中利用光纤布拉格光栅从可调谐激光器中反射出两束相位近似相等的相干光,采用平衡探测产生了毫米波信号,降低了相位噪声和强度噪声对产生的毫米波信号的影响.     

Analyzing the structure of a class of linear automata over a ring $$ Z_{p^k } $$

Basic finite-automaton characteristics are established for the class of all linear automata and information-lossless automata over a ring. The complexities of solving problems of parametric identification and initial-state identification are analyzed. The sets of fixed points for mappings realized by initial automata are characterized. Canonical forms are proposed for linear automata over the ring. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 60–74, May–June 2008.     

MCLP-based methods for improving “Bad” catching rate in credit cardholder behavior analysis

Cardholders’ behavior prediction is an important issue in credit card portfolio management. As a promising data mining approach, multiple criteria programming (MCLP) has been successfully applied to classify credit cardholders’ behavior into two groups. In order to better control credit risk for financial institutes, this paper proposes three methods based on MCLP to improve the “Bad” catching accuracy rate. One is called MCLP with unbalanced training set selection, the second is called fuzzy linear programming (FLP) method with moving boundary, and the third is called penalized multi criteria linear programming (PMCLP). The experimental examples demonstrate the promising performance of these methods.     

旋耕刀传感器的研究

设计了一种供旋耕刀测力用的延伸八角环传感器。该传感器具有良好的线性、较高的灵敏度及较小的滞后现象 ;各被测参数间的交互影响很小 ,可以忽略。     

单苯环氯取代指数法预测二噁类化合物PCDDs的正辛醇/水分配系数

采用单苯环氯取代指数作为氯代二苯并二口恶口英类化合物 (PCDDs)的分子结构描述符 ,通过正向逐步线性回归方法建立了PCDDs的logKow与分子结构描述符之间的定量关系模型。与文献报道的MOD模型相比 ,该模型不仅具有显著的相关性 (n =43,Radj=0 898,SE =0 195 ,在α =0 0 5时 ,F =2 0 45 5 ,p =0 0 0 0 0 ) ,而且对于分子结构具有更好的区分能力。利用建立的模型 ,对没有logKow文献值的其他 33种PCDDs化合物给出了预测值     

低压长袋脉冲袋式除尘器设计与应用

以工业原料尤里卡沥青(EP)为对象，详细论述了低压长袋脉冲袋式除尘器的主要设计环节，着重分析了新型脉冲阀技术。指出了该技术在化肥行业原料干燥、风扫制备等方面的推广应用和发展趋势。     

高温热采井水泥环缺陷对套管安全性的影响分析

针对水泥环缺陷导致套管承受非均匀载荷并引起套管失效的问题,建立了套管、含缺陷水泥环和地层耦合系统有限元计算模型。将温度场与应力场耦合,考虑套管强度降低,计算了水泥环缺陷形状、缺陷环向开度、缺陷深度及缺陷数量对套管安全的影响。应用塑性变形、剩余强度和安全系数来评价水泥环含缺陷井筒中套管的安全性,并分析了套管的失效模式。计算结果表明:完整井筒和水泥环含缺陷井筒中套管的屈服温度相差较大,水泥环缺陷环向开度和深度对套管安全的影响比较大。此研究为揭示套管失效机理提供了依据,对预防套损具有指导意义。     

Subliminal channels in the identity-based threshold ring signature

Subliminal signature schemes enable senders to hide subliminal messages in a digital signature such that no one besides the authorised subliminal message receiver (called designated receiver) can extract subliminal messages from that signature. This paper is the first to construct subliminal channels on the identity-based threshold ring signature scheme. Two types of subliminal channels are proposed. The first is the unknown-sender subliminal channel, wherein the sender is anonymously sending the subliminal message through an identity-based threshold ring signature. Although the designated receiver can extract the subliminal message and confirm that it is from the known ring of signers, he/she cannot identify the real sender. The other proposed subliminal channel is the known-sender subliminal channel in which the designated receiver can identify the actual sender. Furthermore, the proposed unknown-sender subliminal channel can be extended to permit the sender to send multiple subliminal messages to multiple designated receivers via a single threshold ring signature.     

基于主备链路稳定性的节能多径AOMDV-ES路由协议

移动Ad hoc网络中的AOMDV协议是典型的多径按需距离矢量路由协议。由于移动Ad hoc网络资源有限,AOMDV协议洪泛路由发现方式会导致控制开销过大,选择的最短时延路径不够稳定,如果动态维护多条路径则开销更大,会抵消多径路由协议的优势。针对以上问题,结合多径路由和扩展环搜索的思想提出一种基于主备链路稳定性的节能多径路由协议(AOMDV-ES)。通过对AOMDV-ES协议和AOMDV协议在不同场景下进行仿真分析比较,结果显示AOMDV-ES协议的整体性能在路由开销、分组递交率和平均端到端延时方面较AOMDV协议有所改进。     

Polyaniline as a Gas-Sensor Material

Polyaniline (PANI) was synthesized by oxidative polymerization of aniline using ammonium persulfate in an acid medium. The polyaniline salt was converted to base form by treatment with ammonium hydroxide. The polyaniline base was dissolved in N-methyl pyrrolidone (NMP) for film casting. The cast film was doped with HCl for obtaining higher conductivity. Both doped and undoped PANI films were characterized by UV-visible, FTIR, and XRD analyses. The electrical conductivity of the PANI film was studied by a four-point probe method at room temperature. Finally, ammonia gas-sensing characteristics of the prepared polyaniline film were studied by measuring the change in electrical conductivity on exposure to ammonia gas at different concentrations. The influence of concentration of acid during polymerization of aniline and dopant concentration on the gas sensing characteristics of PANI film are reported in this paper.