Assessing students' conceptual understanding using an online three‐tier diagnostic test

When solving a mathematical problem, students who do not have sufficient conceptual understanding may perform poorly and exhibit misconceptions. This study was aimed to examine students' conceptual understanding and significant misconceptions when solving number sense‐related problems. An online three‐tier diagnostic test was administered to 125 fifth‐grade students with varied socio‐economic backgrounds in Hong Kong. Only 14.40% of the students exhibited high performance with high confidence, indicating that these students had a profound conceptual understanding of number sense. In addition, the majority of the students (66.40%) did not demonstrate number sense; these students exhibited several significant misconceptions and could solve the questions only by using a rule‐based method or guessing. Accordingly, most students performed unsatisfactorily on number sense‐related problems. This study is imperative in identifying early predictors and provides information for further compatible interventions in the teaching and learning of number sense in Hong Kong in particular and worldwide in general.     

基于深度残差学习的自动驾驶道路场景理解

随着道路场景理解技术的快速发展，自主驾驶领域取得了长足的进步。在相关任务中，包括道路分割、分类和车辆检测的实时性和准确性是安全性的一个关键问题。为此，提出了一个具有编/解码器网络结构的基于深度残差学习的方法。一方面，编码器网络结构使用不同层次的残差网络来提取高维中的抽象特征，这些特征在接下来的三个任务中共享使用；另一方面，解码器网络结构采用一种子任务的并行计算机制，即道路分割、车辆检测和道路分类任务同时执行。此外，全卷积神经网络用于对提取的图像特征进行上采样以解决道路分割问题。最终，实验结果表明在保证高精度的前提下处理帧率可达到15 fps以上。     

航空装备保障智能化发展认识与探讨

自新一代人工智能技术迅猛发展以来，世界各国在智能领域动作频繁，军事化应用明显有加速之势，给装备保障带来了变革性发展的机遇。紧密围绕作战-装备-技术-保障之间的依托关系，从作战需求、装备特点、装备设计、诊断测试和技术驱动等五个角度梳理了装备保障发展的关键因素，给出了装备保障60余载发展历程的诸多原因和显著成果；通过对未来作战模式和未来作战平台保障需求的前瞻性判断，分析了未来作战需求和装备牵引装备保障转变的典型技术特征；并在装备保障领域人工智能技术的发展和应用现状总结分析的基础上，系统地提出了装备保障智能化发展的建设性意见和建议，为国内装备保障智能化发展探索了一个可能的技术方向。     

Semantics for consistent activation in context-oriented systems

ContextContext-oriented programming languages provide dedicated programming abstractions to define behavioral adaptations and means to combine those adaptations dynamically according to sensed context changes. Some of these languages feature programming abstractions to explicitly define interaction dependencies among contexts. However, the semantics of context activation and the meaning of dependency relations have been described only informally, which in some cases has led to incorrect specifications, faulty implementations and inconsistent system behavior.ObjectiveWith the aim of avoiding faulty implementations and inconsistencies during system execution, this paper proposes both a formal and run-time model of contexts, context activation and context interaction.MethodAs a formal and computational basis, we introduce context Petri nets, a model based on Petri nets, which we found to match closely the structure of contexts in context-oriented systems. The operational semantics of Petri nets permits the modeling of run-time context activations. Existing Petri net analyses allow us to reason about system properties. As validation, we carried out small and medium-sized case studies.ResultsIn the cases explored, context Petri nets served effectively as underlying run-time model to ensure that declared context interaction constraints remain consistent during context manipulation. Moreover, context Petri nets enabled us to analyze certain properties regarding the activation state of particular contexts.ConclusionContext Petri nets thus proved to be appropriate to encode and manage the semantics of context activation, both formally and computationally, so as to preserve the consistency of context-oriented systems.     

Reviews of clean coal conversion technology in China:Situations & challenges

It is important to develop the advanced coal to chemicals industry (ACCI) against a backdrop of coal-based energy structures,excessive imported oil and natural gas,and strict environmental con-straints in China.In this study,the technology and industry of China's ACCI are reviewed to explain the effect of using coal to replace oil and natural gas,and the corresponding resource and environmental burdens that this will create.Development trends in technology and industry are also proposed to explore future scenarios.The review shows that although excellent progress has been made on an indus-trial scale,demonstrative level,and in terms of technology and equipment,the lack of strategic under-standing,severe external constraints,partly underdeveloped technologies,and weak foundations must be immediately addressed.Therefore,it is necessary to clarify the importance that the ACCI has on the energy revolution and energy system.Based on technological innovation,a variety of external factors should be considered as a whole with emphasis on filling the knowledge gap of theoretical foundations and industry standards to support high-quality development for ACCI.     

谈我省煤炭专网通信及信息网络系统改造

通过对我省煤炭专网通信与信息系统应用现状及存在问题的分析,论述了建立综合信息网络系统的必要性和可能性,并初步阐述了综合信息网络系统建设应遵循的规划目标和原则。     

CBE教改在职业教育中的应用

通过矿山电气化专业CBE教改过程 ,系统介绍了CBE教改实施情况并提出了自己的建议     

浅谈危险废物处理处置工程的规划及设计

根据笔者近10年来在危险废物处理领域的体会,在探讨了危险废物处理处置工程规划和设计应遵循的原则、处理处置工程一般应包括的工程设施的基础上,重点探讨了危险废物处理处置工程的物流体系、规划和设计的具体方案及其应注意的问题。     

The effects of land use on fluvial sediment chemistry for the conterminous U.S. - results from the first cycle of the NAWQA Program: trace and major elements, phosphorus, carbon, and sulfur

In 1991, the U.S. Geological Survey (USGS) began the first cycle of its National Water Quality Assessment (NAWQA) Program. The Program encompassed 51 river basins that collectively accounted for more than 70% of the total water use (excluding power generation), and 50% of the drinking water supply in the U.S. The basins represented a variety of hydrologic settings, rock types (geology), land-use categories, and population densities. One aspect of the first cycle included bed sediment sampling; sites were chosen to represent baseline and important land-use categories (e.g., agriculture, urban) in each basin. In total, over 1200 bed sediment samples were collected. All samples were size-limited (< 63 µm) to facilitate spatial and/or temporal comparisons, and subsequently analyzed for a variety of chemical constituents including major (e.g., Fe, Al,) and trace elements (e.g., Cu, Zn, Cd), nutrients (e.g., P), and carbon. The analyses yielded total (≥ 95% of the concentrations present), rather than total-recoverable chemical data.Land-use percentages, upstream underlying geology, and population density were determined for each site and evaluated to asses their relative influence on sediment chemistry. Baseline concentrations for the entire U.S. also were generated from a subset of all the samples, and are based on material collected from low population (≤ 27 p km^− 2) density, low percent urban (≤ 5%), agricultural or undeveloped areas. The NAWQA baseline values are similar to those found in other national and global datasets. Further, it appears that upstream/underlying rock type has only a limited effect (mostly major elements) on sediment chemistry. The only land-use category that appears to substantially affect sediment chemistry is percent urban, and this result is mirrored by population density; in fact, the latter appears more consistent than the former.