智能电磁感知的若干进展

智能电磁感知是电磁探测与成像的系统化和智能化延伸,是安全检查、生物医学、物联网等领域的基础性、关键性和共性问题.近年来,挖掘利用人工电磁材料和人工智能在电磁波调控与数据信息调控方面的强大能力,将其有机结合,并系统地引入电磁感知领域,发展了低成本、高性能的智能电磁感知体制,为电磁感知的进一步发展提供了关键理论和技术支撑....     

Drying of Sewage Sludge During Composting in an Updraft Dryer with the Concept of Using Self-Energy Generated Within the System

An innovative technology for sewage treatment systems is proposed. A mixture of sewage sludge and char particle is subjected to drying in the progress of composting in an updraft column. Exothermic heat generated during composting is utilized for energy of sludge drying. The char particle in the mixture contributes to enhancement of composting and drying rate. This study presents drying and composting behaviors of sludge to examine the effect of char addition. A fundamental drying experiment was carried out by hot-air heating of the sample in a small vessel. The drying characteristic curve for a mixture of sludge and char was greater than the sample of only sludge over a whole period if the drying rates were compared with the same moisture content. The drying behavior could be analyzed with a reasonable agreement by the water front receding model. The enhancement effect of drying and composting of sludge by char addition was confirmed by examination using a pilot scale of the updraft column whose volume was 50 m³. Sludge with 400% dry base (80% wet base) in moisture content could be dried successfully to lower moisture content than 67% dry base (40% wet base) only by exothermic heat during composting without supplying any auxiliary energy from the outside, and the treatment time was reduced by mixing char in sludge. The behavior was analyzed with a satisfactory agreement by a theoretical model employing moisture diffusion parameters determined from the drying characteristic curve.     

Absorption of electromagnetic waves by the dust particles in a plasma

Inthispaperwestudytheabsorptionofelectromagneticwavesbythechargeddustgrainsimmersedinambientplasma.Theelectromagneticwavepropagationindustyplasmahasbeenahottopicinrecentyears.Mostpaperspublishedsofarfocusontheincreaseofthewavescatteringinadustyplasma[1—4].InthispapertheenergylossoftheincidentelectromagneticwavecausedbyalongitudinalscatteringfieldoftheDebyescatteringispresented.ThephysicalpictureoftheproblemisachargeddustgrainwhichisassumedtobesphericalofradiusasurroundedbyascreeningDebyesphe…     

高新技术开发区的城乡统筹社区规划策略——以安康高新技术产业开发区为例

城乡统筹发展是我国目前城乡规划领域的总体方针之一,既包括产业布局、用地调整等方面,又包括居民住房保障、社区构建等方面,其要求充分考虑农村的生产、生活特征,科学合理地布置各类居住组团及社区。安康高新技术产业开发区城乡统筹社区规划从"城乡统筹"和"社区"两个角度入手,遵循城乡统筹发展要求的原则,尝试构建一种新型的农村社区、农村+城市社区,保障搬迁居民、原住民的住房需求。城乡统筹社区规划为我国的城乡统筹提供一种新思路,为保障人们的住房需求提供一种新模式,具有一定的借鉴意义。     

One-bit quantization is good for programmable coding metasurfaces

Science China Information Sciences -     

基于互质阵列雷达技术的近距离目标探测方法(英文)

一组(M, N)互质阵列由两组结构化排列的子阵列构成:一组包括M个天线单元, 另一组包括N个天线单元。互质阵列稀疏天线仅需要M+N1个收发天线单元就可实现对O(MN)个远距离目标的识别。在相同分辨条件下, 互质阵列雷达技术可利用更少的收发单元来识别更多的雷达目标。因此互质阵列雷达技术能够极大地降低传统雷达收发系统的复杂度。但是, 现有文献中所讨论的互质阵列雷达技术均基于远场近似假设, 当探测近距离目标时, 会由于目标邻近天线单元而产生严重的探测误差。为了解决上述问题, 该文将标准的互质阵列雷达技术的适用范围扩展到用于解决近距离目标探测。该文论证了(M, N)互质阵列雷达技术能够以4k0/MN空域分辨率恢复[2k0, 2k0]空域范围内的目标信息, 其中k0表示自由空间波数, 是场景因子。由此可见(M, N)互质阵列能够以/4的方位向分辨率获得O(MN)个近距离目标方位向位置信息。该文进一步论证了互质阵列雷达技术在穿墙成像中的适用性。最后, 该文提供了一组数值仿真实验结果, 验证了互质阵列雷达技术对于近距离目标探测的有效性。      

Design of sparse array for mad imaging based on maximizing information capacity

In past years, growing efforts have been made to the rapid interpretation of magnetic field data acquired by a sparse synthetic or real magnetic sensor array. An appealing requirement on such sparse array arranged within a specified survey region is that to make the number of sensor elements as small as possible, meanwhile without deteriorating imaging quality. For this end, we propose a novel methodology of arranging sensors in an optimal manner, exploring the concept of information capacity developed originally in the communication society. The proposed scheme reduces mathematically the design of a sparse sensor array into solving a combinatorial optimization problem, which can be resolved efficiently using widely adopted Sinmltaneous Perturbation and Statistical Algorithm （SPSA）. Three sets of numerical examples of designing optimal sensor array are provided to demonstrate the performance of proposed methodology.     

PVC塑料砂浆导热性研究

水泥砂浆中加入聚氯乙烯(PVC)塑料骨料可以改善砂浆的保温性能,为了探索热流在砂浆中的传输方式及研究 PVC 塑料骨料对水泥砂浆导热系数的影响,建立了水泥砂浆的串联导热模型与并联导热模型,根据实验结果进一步提出了 PVC 塑料砂浆串并联混合导热模型,研究表明由串并联混合模型计算出的理论值与实测值呈现出了良好的一致性。     

浅析泥土对不同结构聚羧酸减水剂的吸附规律

目前,混凝土减水剂主要以聚羧酸和萘系两种为主。聚羧酸减水剂(PCEs)在应用过程中对泥土过于敏感,性能急剧下降,而萘系具有很好的抗泥性,这也是萘系减水剂在砂石含泥量较高的商砼领域一直占据主导地位的重要原因。要在商砼领域大规模推广聚羧酸减水剂,增强其抗泥性是关键所在。利用紫外可见吸收光谱分析手段,研究泥土对不同结构的聚羧酸减水剂的吸附规律,并且研究了聚羧酸减水剂对不同含泥量砂浆的分散性能,实验发现水泥浆显著提升了泥土对聚羧酸减水剂的饱和吸附量,并初步发现短主链、短侧链的聚羧酸减水剂抗泥效果相对较好。     

侧限条件下原状黄土增湿特性研究

目前,对侧限条件下原状黄土增湿过程中的变形和持水特性研究还较少。以新疆伊犁原状黄土为对象,采用固结仪开展了不同竖向压力作用下的分级增湿试验和湿陷试验。在分级增湿试验中,研究了增湿过程中持水特性以及静止土压力系数的变化规律,提出了侧限条件下土水特征曲线模型以及静止土压力系数的表达式;引入"增湿水平"这一变量描述土体的含水状态,研究了增湿变形与增湿水平的相关关系。最后通过比较增湿试验(单线法)和湿陷试验(双线法)所得到的增湿水平与增湿变形系数关系曲线,验证了两种试验方法在黄土增湿变形研究中的等效性。