浅析我国居住空间分异现象及对策

文章阐述了居住空间分异现象,分析了居住空间分异的动力机制以及居住分异造成的影响,提出了通过规划多中心城市结构,合理配置居住区用地资源;推行廉租房、经济适用房政策;完善社区保障体制,提倡多样交往空间等措施合理引导居住空间分异,促进我国城市居住空间的健康发展。     

Spectral efficiency of distributed antenna system with random antenna layout

The downlink capacity potential of a distributed antenna system (DAS) with random antenna layout is investigated. A low complexity sub-optimal power allocation scheme among transmit antennas is proposed. Simulation results show that with the same antenna density DAS outperforms a co-located antenna system (CAS) in terms of average and outage spectral efficiency.     

如何科学合理地绘制罐区自动化操作界面图

针对炼油厂的实际情况介绍了罐区油品在线调合和移动自动化操作系统界面图(TFG图)与传统的D6操作界面图的区别，以及TFG图的绘制原则。     

威林斯頓盆地奥陶系白云岩储层同位素与成岩作用分析

威林斯顿(Williston)盆地上奥陶统红河群灰岩由于不同期次的白云岩化作用,形成了4种不同产状类型的白云石:纹层状微晶白云石、生物钻孔充填白云石,基质白云石、马鞍状白云石,只有基质白云石因具晶间孔而成为储层。4种白云石的氧、碳、锶同位素组成均与晚奥陶世的海水同位素组成有较大区别。岩石学和地化研究表明,前2种白云石的白云岩化流体应来自晚奥陶世海水,但今天的同位素组成反映了后期的改造或重构;储层白云石形成的温度稍高,时间可能稍晚,白云岩化流体可能来源于志留纪海水、或寒武—早中奥陶世海水、或深部热液;马鞍状白云石的形成应与深部热液有关。白云岩化成层状发生可能与薄的富含有机质的Kukersite页岩有关。      

Privacy-aware collection of aggregate spatial data

Privacy concerns can be a major barrier to collecting aggregate data from the public. Recent research proposes negative surveys that collect negative data, which is complementary to the true data. This opens a new direction for privacy-aware data collection. However, the existing approach cannot avoid certain errors when applied to many spatial data collection tasks. The errors can make the data unusable in many real scenarios. We propose Gaussian negative surveys. We modulate data collection based on Gaussian distribution. The collected data can be used to compute accurate spatial distribution of participants and can be used to accurately answer range aggregate queries. Our approach avoids the errors that can occur with the existing approach. Our experiments show that we achieve an excellent balance between privacy and accuracy.     

利用电熔爆技术加工钢轨的关键问题研究

针对铁路钢轨目前存在的肥边，提出用电熔爆技术加工钢轨的问题。通过对钢轨硬度、强度实验结论叙述。钢轨用电熔爆技术加工的工作原理、加工速度、精度、经济性及安全、环保等方面的分析、研究。证明此加工方案是可行的。     

两色金鸡菊的遗传毒性及其食用安全性评价

目的 检测两色金鸡菊的遗传毒性，为其食用安全性评价提供研究数据。方法 以两色金鸡菊（水提取物）为受试物，采用细菌回复突变试验、小鼠淋巴瘤细胞TK基因突变试验（MLA）分别在代谢活化（+S9）和非代谢活化（-S9）条件下检测；以两色金鸡菊（粉末）为受试物，采用小鼠骨髓微核试验检测。细菌回复突变试验采用平板掺入法，检测1.25、2.5、5、10 mg/皿4个剂量诱发鼠伤寒沙门氏菌TA98、TA100、TA1535、TA1537及大肠杆菌WP2uvrA的his^-/trp^-回复突变能力；MLA采用微孔法，检测1.5、2.0、2.5、3.0、3.5 mg/mL 5个浓度在±S9/3 h处理条件下是否诱发L5178Y细胞tk^+/-基因突变频率（MF）增加，评价对测试细胞的损伤作用；小鼠骨髓微核试验：间隔24 h连续3次经口灌胃给予CD-1小鼠900、1800、3600 mg/kg两色金鸡菊粉末（200目），并在末次给予后18~24 h取材，计数2000个嗜多染红细胞中含微核细胞，计算微核细胞率。结果 +、-S9条件下，1.25~10 mg/皿（生药剂量8.33~66.67 mg/皿）诱发5株测试菌的回变菌落数与灭菌注射用水阴性（溶媒）对照比较，无明显增加；1.5~3.5 mg/mL（生药浓度10~23.33 mg/mL）诱发的MF明显增加并具有浓度相关性，+S9条件下的3.0、3.5 mg/mL浓度组诱发的T-MF、S-MF达到阴性对照组的3倍以上，且以小集落突变体为主；900、1 800、3 600 mg/kg剂量组平均微核率分别为0.85±0.58、1.10±0.97、1.45±1.12，与去离子水阴性对照组比较无显著性差异。结论 两色金鸡菊（水提物）无论代谢活化与否均可诱发L5178Y细胞tk^+/-基因位点突变并导致染色体损伤，提示对人体具有潜在的遗传毒性。     

Error control schemes for networks: An overview

In this paper, we investigate the issue of error control in wireless communication networks. We review the alternative error control schemes available for providing reliable end-to-end communication in wireless environments. Through case studies, the performance and tradeoffs of these schemes are shown. Based on the application environments and QoS requirements, the design issues of error control are discussed to achieve the best solution. This revised version was published online in June 2006 with corrections to the Cover Date.     

Highly efficient organic tandem solar cell based on SubPc:C70 bulk heterojunction

Highly efficient organic tandem solar cell with peak power conversion efficiency (PCE) of 7.66% has been demonstrated by simply stacking two same boron subphthalocyanine (SubPc):C₇₀ bulk heterojunction devices, with a high active inter-connecting layer composed of bathophenanthroline (Bphen)/Silver/hexadecafluoro-copper-phthalocyanine (F₁₆CuPc)/MoO₃. We find that F₁₆CuPc plays an important role which extends the recombination zone, facilitates the extraction of hole and the carrier recombination. The measured PCE of the tandem solar cell corresponds to a 38% increase compared to that the optimal single cell.     

Browsing large online data tables using generalized query previews

Companies, government agencies, and other organizations are making their data available to the world over the Internet. They often use large online relational tables for this purpose. Users query such tables with front-ends that typically use menus or form fillin interfaces, but these interfaces rarely give users information about the contents and distribution of the data. Such a situation leads users to waste time and network/server resources posing queries that have zero- or mega-hit results. Generalized query previews enable efficient browsing of large online data tables by supplying data distribution information to users. The data distribution information provides continuous feedback about the size of the result set as the query is being formed. Our paper presents a new user interface architecture and discusses three controlled experiments (with 12, 16, and 48 participants). Our prototype systems provide flexible user interfaces for research and testing of the ideas. The user studies show that for exploratory querying tasks, generalized query previews can speed user performance for certain user domains and can reduce network/server load.