热敏微型打印机设计原理

介绍了热敏微型打印机的基本工作原理、结构和打印头的机电特性及设计中需注意的问题。     

Low Volume-Expansion,Insertion-Type Layered Silicate Hierarchical Structure For Superior Storage Of Li,Na, K

A hierarchical structure is successfully synthesized by coating polypyrrole (PPy) on the surface of carbon/saponite superlattice (denoted as PPy@C/SAP), and applied as low volume-expansion insertion-type anode for Li, Na, K storage.The synergistic effect of metal Ni, Fe doping, carbon/silicate superlattice, abundant oxygen vacancies and PPy coating leads to a good electronic conductivity and large current discharging capability. As a Si-based material, PPy@C/SAP has excellent storage capability for Li (659 mAh g⁻¹ after 1000 cycles at 2 A g⁻¹ and 550 mAh g⁻¹ after 1000 cycles at 5 A g⁻¹), Na (maximum specific capacity of 533 and 327 mAh g⁻¹ after 50 cycles) as well as K (236 mAh g⁻¹ after 100 cycles). XPS, XANES, XRD, FTIR, HRTEM, SEM are used to detect the hybrid mechanism (bulk insertion and surface conversion) with a volume expansion as low as 9%. Insertion reaction driven by valence state change of Ni, Fe, Si (Ni⁰⇔Ni²⁺, Fe0⇔Fe³⁺, Si²⁺⇔Si⁴⁺) in laminates and conversion reactions between LiOH/Li₂CO₃ and LiH/Li₂C₂ catalyzed by Ni° contribute to the high performance. In the whole electrochemical process, layered structure is retained while the conversion reactions of LiOH (prodeced by laminates dehydroxylation) and Li₂CO₃ (electrolyte decomposition) cause the dynamic evolution of solid ectrolyte interphase. This study develops a promising Si-based anode material for lithium ion batteries, sodium ion batteries and potassium ion batteries, which is significant for designing long cycle life rechargeable batteries.     

鞍钢高炉合理配矿试验研究

通过对鞍钢进口块矿、几种人造富矿及它们的复合高炉炉料冶金性能、软熔及熔融滴落性能的对比试验研究，分析了各种复合炉料的性能及对吨铁成本的影响，提出了鞍钢大型高炉最佳的炉料结构。     

A Unified Co-Processor Architecture for Matrix Decomposition

QR and LU decompositions are the most important matrix decomposition algorithms. Many studies work on accelerating these algorithms by FPGA or ASIC in a case by case style. In this paper, we propose a unified framework for the matrix decomposition algorithms, combining three QR decomposition algorithms and LU algorithm with pivoting into a unified linear array structure. The QR and LU decomposition algorithms exhibit the same two-level loop structure and the same data dependency. Utilizing the similarities in loop structure and data dependency of matrix decomposition, we unify a fine-grained algorithm for all four matrix decomposition algorithms. Furthermore, we present a unified co-processor structure with a scalable linear array of processing elements (PEs), in which four types of PEs are same in the structure of memory channels and PE connections, but the only difference exists in the internal structure of data path. Our unified co-processor, which is IEEE 32-bit floating-point precision, is implemented and mapped onto a Xilinx Virtex5 FPGA chip. Experimental results show that our co-processors can achieve speedup of 2.3 to 14.9 factors compared to a Pentium Dual CPU with double SSE threads.     

Learning Query Ambiguity Models by Using Search Logs

dentifying ambiguous queries is crucial to research on personalized Web search and search result diversity. Intuitively, query logs contain valuable information on how many intentions users have when issuing a query. However, previous work showed user clicks alone are misleading in judging a query as being ambiguous or not. In this paper, we address the problem of learning a query ambiguity model by using search logs. First, we propose enriching a query by mining the documents clicked by users and the relevant follow up queries in a session. Second, we use a text classifier to map the documents and the queries into predefined categories. Third, we propose extracting features from the processed data. Finally, we apply a state-of-the-art algorithm, Support Vector Machine (SVM), to learn a query ambiguity classifier. Experimental results verify that the sole use of click based features or session based features perform worse than the previous work based on top retrieved documents. When we combine the two sets of features, our proposed approach achieves the best effectiveness, specifically 86% in terms of accuracy. It significantly improves the click based method by 5.6% and the session based method by 4.6%.     

非支配排序遗传算法的改进

NSGA-Ⅱ（Non-dominated Sorting Genetic Algorithm）算法针对多目标优化问题,提出了非劣分类分层,引进拥挤度和拥挤度比较算子,通过精英选择策略,这样可使非劣前沿向Pareto前沿靠近,同时使解集具有更好的多样性。笔者对NSGA-Ⅱ算法的原理进行了系统的学习和研究,结合国内外最新的研究情况,实现了该算法并进行了一些改进,以期获得更好的效果,最后用多目标标准测试函数进行了实验分析。     

IPv6 over DVB在远程教育中的应用

构建IPv6 over DVB体系框架,可以在下一代互联网中利用卫星等广播信道实施远程教育。该体系框架包括“支持IPv6的教育资源管理与发布系统”、“IPv6 over DVB传输系统”以及“IPv6 over DVB在远程教育中的应用示范”3个部分。实现了将IPv6互联网中的教育资源通过卫星链路发布到目前尚无网络覆盖的1 000所农牧村中小学。给出了设计方案和部署策略。     

波谱学在催化剂表征中的应用

介绍了红外光谱，拉曼光谱，核磁共振，X光电子能谱的表征能力及其在表征催化剂中的作用。红外和拉曼光谱可用于研究表面分子和载体结构；核磁共振可得到分子或原子团所处的化学环境；X光电子能谱可以了解元素的化学态，了解和掌握这些表征有助于进行催化剂的研究。     

面向大数据的图模式挖掘概率算法

在当今大数据时代,MapReduce等大数据处理框架处理数据能力有限,其在处理有关图的数据时常常显得缓慢低效,典型如3-clique计数问题,故需要探究一种高效的算法处理这类clique计数问题。由于在前人文献中对3-clique计数问题已有深入探讨,故针对该问题的扩展版本—4-clique计数问题进行探究。在一个启发式的想法下提出了基于邻边采样的概率采样算法,利用切诺夫不等式证明该算法在近似条件下只需要一定数量的采样器作为相对误差的性能保证。通过实验评估对比发现,相对于传统精确算法,概率采样算法虽然在结果上损失了少量的精度,但在算法运行时间和空间占用上具有巨大的优势。最后得出其在实际应用中具有巨大实践价值的结论。     

Process‐based modelling of tributary mouth sandbar evolution in a high sediment‐load reservoir

Sedimentation always leads to loss of reservoir storage. This is an important issue for reservoir management, particularly for reservoirs on the Yellow River. As a result of sedimentation, sandbars are frequently found at the mouth of tributaries in reservoirs. The evolution of a tributary mouth sandbar, including its formation and scouring, plays a key role in reservoir sedimentation. However, there are few effective numerical models reported in previous studies for tributary mouth sandbar evolution in reservoirs. In this study, we propose two modules for evolution processes of mouth sandbars: one for intrusion and sedimentation and the other for scouring process. Both modules coupled turbidity current, open‐channel flow, and flow exchanges between the main stream and tributaries. Field measurements and laboratory experiments with different set‐ups were used to test the capabilities of the two proposed modules. By coupling formation and scouring modules with a 2D morphodynamic model in reservoirs, we successfully built a novel numerical model to simulate the evolution processes of tributary mouth sandbars in reservoirs. A field‐scale application of the coupled model was undertaken to simulate evolution of tributary mouth sandbars in the Xiaolangdi Reservoir, Yellow River. The results indicate that the numerical model in this study is more practical than previous models and could provide great support for optimizing reservoir operation in other systems.