Circular SAR processing using an improved omega-k type algorithm

An improved circular synthetic aperture radar (CSAR) imaging algorithm of omega-k (ω-k) type mainly for reconstructing an image on a cylindrical surface is proposed. In the typical CSAR ω-k algorithm, the rage trajectory is approximated by Taylor series expansion to the quadratic terms, which limits the valid synthetic aperture length and the angular reconstruction range severely. Based on the model of the CSAR echo signal, the proposed algorithm directly transforms the signal to the two-dimensional (2D) wavenumber domain, not using approximation processing to the range trajectory. Based on form of the signal spectrum in the wavenumber domain, the formula for the wavenumber domain interpolation of the ω-k algorithm is deduced, and the wavenumber spectrum of the reference point used for bulk compression is obtained from numerical method. The improved CSAR ω-k imaging algorithm increases the valid synthetic aperture length and the angular area greatly and hence improves the angular resolution of the cylindrical imaging. Additionally, the proposed algorithm can be repeated on different cylindrical surfaces to achieve three dimensional (3D) image reconstruction. The 3D spatial resolution of the CSAR system is discussed, and the simulation results validate the correctness of the analysis and the feasibility of the algorithm.     

考虑消费者渠道偏好的多期闭环供应链网络均衡

在多个规划期情形下,研究了由制造商层、零售商层、需求市场层和回收商层组成的闭环供应链网络均衡问题.所有制造商生产同质产品,利用双渠道分销产品以满足市场需求.两种交易渠道间存在竞争,消费者对电子商务和零售商两种购物渠道存在不同偏好.利用变分不等式和互补理论刻画了网络中各成员的最优经济行为,建立了供应链网络均衡模型,并运用修正投影收缩算法求解.结合算例探讨了单/双渠道、渠道间的竞争强度因子、消费者对电子商务渠道的偏好系数及制造商的强制回收量约束对供应链网络各成员及网络均衡的影响.结果表明:当消费者偏好大于一定程度时,双渠道对制造商有利,而对零售商不利;电子渠道竞争强度因子对网络成员的利润影响较大,制造商应加大网络等方面投资;当消费者对电子交易渠道的偏好增加时,制造商利润先减后增,制造商在开设电子商务时应把握合适的切入时机,且不要因暂时的利润降低而关闭电子营销方式;单/双渠道情形下,政府的强制性回收量约束均会对制造商带来不利影响,当回收量约束超过某一值时所有成员会动态调整其策略而改变供应链网络的均衡状态.通过研究,以期对闭环供应链相关领域的研究和企业决策有一定借鉴.     

Multiple constraints QoS multicast routing optimization algorithm in MANET based on GA

Usually multiple quality of service （QoS） guarantees are required in most multicast applications. This paper presents a multiple con-straints algorithm for multicast traffic engineering in mobile ad hoc networks （MANET）. The proposed algorithm is a new version of multiple constraints QoS multicast routing optimization algorithm in MANET based on genetic algorithm （MQMGA）. The proposed MQMGA can optimize the maximum link utilization, the cost of the multicast tree, the selection of the long-life path, the average delay and the maximum end-to-end delay. Experimental result shows that the approach is efficient, has promising performance in multicast traffic engineering and for evaluating the route stabilitv in dvnamic mobile networks.     

A new technique for synthesis of 2,4-dichloro-thieno[3,2-d]pyrimidine

3-Amino-2-methoxycarbonylthiophene used as the main raw material,an intermediate(thiofuran siamese) 2,4-dichloro-thieno[3,2-d]pyrimidine was synthesized.The prod-uct was characterized by nuclear magnetic resonance(NMR).The first step yield was 84%(190 ℃) and the second step yield was 81.4%(105 ℃,m(intermediate):m(phosphorus oxychloride) = 1:6.4).The raw product was refined with a unique refining process,which can enhance the purity up to 99.5% to meet the requirement of condi-tions for the development and research of thiofuran siamese as a new medicine of anticarcinogen.Contrasted with the traditional technique,this process featured with cheap raw materials,possible for solvent recovery and reuse,low comprehensive cost,and suit-able for production on certain scale.     

萨拉乌苏河流域钙结核中碳氧同位素特征及古环境意义

通过对萨拉乌苏河流域酒坊台剖面中普遍发育的钙结核进行碳、氧同位素分析,结果显示各岩性组中同位素分布特征差异较大,无明显线性关系。利用钙结核中碳同位素值推算了不同岩性组中C_3和C_4植物的相对贡献量,结合孢粉数据,探讨了不同气候条件下植被演变情况,这与邻区的黄土高原研究成果基本吻合。同时,利用氧同位素和温度的经验公式,定量恢复了倒数第二次冰期-末次冰期的温度变化,其中末次间冰期表现为相对温暖的气候特征。总之,利用钙结核的碳氧同位素可作为定量恢复古温度、古植被的一种有效方式,但需要注意与其他指标进行综合对比分析。     

Behaviors of helium in vanadiu m: Stabil ity, diffusi on, vacancy trapping and ideal tensi le strength

The behaviors of helium in vanadium including stability,diffusion,and its interaction with vacancy as well as its effects on the ideal tensile strength was investigated by a frst-principles method.The activation energy barrier of helium was calculated to be 0.09 eV,which is consistent with the experimental result.The results indicated that the vacancy can lead to a directed helium segregation into the vacancy to form a helium cluster since the vacancy provides a "lower atomic and electron density region" as a large driving force for helium binding.It is easy for a mono-vacancy to trap helium and form a Hen V complex.The frst-principles computational tensile test demonstrates that helium obviously decreased the tensile strength of vanadium.     

面向产品设计的企业知识管理模式

研究了产品设计过程中的知识建模与知识管理问题，提出了面向产品设计的企业知识管理模式．作为设计结果的物理模型不仅表达了设计方案，更是产品设计知识的载体．除了几何信息以外，设计结果还包括产品功能需求、工程约束、设计经验和规则等．基于知识构件建立了产品设计知识库．设计知识能够在两个层次上被重用，一是知识构件层，二是知识项层．     

浅议高等专科学校英语教学

针对高等专科学校诸方面的特性,分析了高等专科学校英语教学中所面临的问题,提出了相应的解决方法,以期从根本上提高学生的英语综合能力。     

一株产氢光合细菌的筛选及培养条件的优化

通过平板划线法从猪粪废水中分离纯化得到一株产氢光合细菌PSB-ZF1,对其菌体进行染色观察、生理生化试验以及活细胞吸收光谱的测定,初步鉴定菌属于红螺菌科红螺菌属(Rhodospirillum)光合细菌;对菌培养过程中的营养条件实验分析后获得的最优培养基配方为:乙酸钠2.0 g,氯化铵1.0 g,碳酸氢钠0.5 g,氯化钠1.0 g,磷酸二氢钾0.2 g,六水氯化镁0.2 g,T.M储液1 m L,酵母膏0.8 g,蒸馏水1 000 m L;考察环境因素对菌种生长的影响,发现光合细菌PSB-ZF1在搅拌状态下,接种量为10%,光照强度为3 000lux,溶解氧量为2.02 mg/L,初始pH为7.0时生长状态最佳;获得高浓度的PSB-ZF1菌液有利于后续产氢实验。     

1∶5滚动实验台轮轨力连续测量系统

轮轨作用力是评价铁道车辆安全性的主要指标.针对1∶5小比例滚动实验台,开发了轮轨力连续测量系统.首先使用有限元分析和应变实验,得到小比例轮对的最佳测点位置.根据测点的应变输出特性,提出小比例滚动台的轮轨力连续测量方案:轮轨横向力采用轮测法测量,再结合轴测法测量轮轨垂向力.在横向力测量中,一侧车轮采用简易余弦桥,另一侧车轮采用直流桥.研制了小比例测力轮对,静态试验结果说明简易余弦桥的测试精度较高.论文最后给出了1∶5滚动实验台轮轨力的测量结果.