The Effect Of Different Presentation Formats Of Hypertext Annotations On Cognitive Load, Learning And Learner Control

This dissertation study was intended to verify whether the positive effects of the roll-over annotation presentation format on reducing cognitive load and enhancing vocabulary and comprehension of 5th-grade children (Morrison, 2004) can be extended to college students\u27 learning from a web-delivered text. In order to answer this research question, relevant constructs, such as cognitive load, learner control and learning, have been examined in this experimental study of 149 undergraduate students in a state university at College of Education. No single effect of annotation presentation format on cognitive load was found, but an interaction effect on cognitive load was revealed between annotation presentation formats and pre-existing knowledge in this study of online education, similar to the interaction effect between annotation presentation formats and learners\u27 reading experience found in traditional textbook learning (Yeung, Jin and Sweller, 1998; Yeung, 1999). Besides, students\u27 computer experience also had a significant impact on their perceived cognitive load. One more key finding from this study was that the embedded annotation presentation format generated the least learner control, significantly different from other annotation presentation formats. In conclusion, an adaptive approach to the design of annotation presentation formats is recommended, for example, individual differences including learners\u27 familiarity with content should be considered along with different annotation presentation formats so as to reduce learners\u27 overall cognitive load. Additionally, learners\u27 computer experience should be examined when hypertext annotations are used. Finally, choices of annotation presentation formats should be well-conceived to balance cognitive load, learning, and learner control

Biochemical and structural characterization of Cren7, a novel chromatin protein conserved among Crenarchaea

Archaea contain a variety of chromatin proteins consistent with the evolution of different genome packaging mechanisms. Among the two main kingdoms in the Archaea, Euryarchaeota synthesize histone homologs, whereas Crenarchaeota have not been shown to possess a chromatin protein conserved at the kingdom level. We report the identification of Cren7, a novel family of chromatin proteins highly conserved in the Crenarchaeota. A small, basic, methylated and abundant protein, Cren7 displays a higher affinity for double-stranded DNA than for single-stranded DNA, constrains negative DNA supercoils and is associated with genomic DNA in vivo. The solution structure and DNA-binding surface of Cren7 from the hyperthermophilic crenarchaeon Sulfolobus solfataricus were determined by NMR. The protein adopts an SH3-like fold. It interacts with duplex DNA through a β-sheet and a long flexible loop, presumably resulting in DNA distortions through intercalation of conserved hydrophobic residues into the DNA structure. These data suggest that the crenarchaeal kingdom in the Archaea shares a common strategy in chromatin organization

The Effect Of Hypertext Annotation Presentation Formats On Perceived Cognitive Load And Learner Control

The impact of hypertext presentation formats on learner control and cognitive load was examined in this study using Campbell and Stanley\u27s (1963) Posttest Only Control Group design. One hundred eightysix undergraduate students were randomly assigned to read a web-based text with no annotations, online glossary annotations, embedded annotations, rollover annotations, or annotations with multiple formats. One of the findings from this study is that the embedded annotation presentation format was ranked the lowest in learner control among the different presentation formats; that is, embedded annotation seemed to provide less control or choices to students in accessing annotations. Moreover, a negative relationship was revealed between the overall cognitive load and learner control as generated by different annotation presentation formats

China's institution-driven energy strategy and oil security

本文要旨在回答中國大陸的能源戰略是如何形成，並探討此一戰略如何影響中國大陸的石油安全。本文主從歷史制度主義的觀點主張中國能源體制是決定中國的石油戰略最重要的因素。解釋中國的能源部門在經濟改革與國際化的內、外部環境下，產生制度變遷，進而形成不同時期的石油戰略。在回答中國大陸日益龐大的石油需求與進口石油依賴，使得政府制訂出提升能源使用效率、節約能源、能源多元化與確保海外石油供應 但由於中國為保護國有石油企業的壟斷角色，對於「迎進來」的市場進入條件設下許多條件限制，對外又採取積極的石油外交，使得國際社會對中國產生重商主義與保護主義的疑慮。 中國的能源部門自1980年以來已經歷幾個階段的改革，第一階段是從1982年至1987年，強調要計畫經濟為主、市場力量為輔的能源制度改革；第二階段是從1988至1992年，重點在於國有企業的改革，鼓勵國有企業集團化；第三階段是從1993至1997年，重點在政企分離，並把配置資源的基礎性職能轉移給市場；第四階段是從1998至2002年，重點在加強國有資產的監管與國有企業經營，並初步建立宏觀能源調控體系；第五階段則是自2003年以降，主要的改革目標在建立跨部門的能源協調機制與對外的競爭力。 本文但由於「漸進主義」式的制度變遷使得能源部門體制改革仍存在許多問題，諸如能源部門分散、能源監管部門眾多、國家安全思維與既得利益等，使得政府部門考量其能源安全時，政府干預仍多於市場思維，即便自改革開放以來國家能力已不斷衰退。但在能源辦與發改委能源局的人力有限以及能源部門缺乏效率的情形下，擁有龐大資源的三大國有石油企業（中石油、中石化、中海油）無疑「挾持」政府的決策，例如理論上中央政府可完全控制與審核國有企業的海外投資，但實際國有企業通常是在海外投案案定局後才通知發改委與國務院。中國的能源決策中的缺乏效率常來自於既得利益者的把持，而不願在整體的政治與經濟政策上肩負起更多的政策責任，例如中央政府與國企對於戰備儲油到底由誰出資的內部爭論。 未來中國的能源戰略會持續採取「迎進來、走出去」的方向；近年來政府試圖改革其能源決策程序，透過建立跨部會的決策協調機制試圖重奪能源決策的主導性，因此於2005年5月正式成立「能源領導小組」，並積極透入政府能源白皮書與能源相關法案的草擬，政府的舉動等於是將能源政策的制訂再度「中央化」。未來中國能源戰略的最大挑戰仍來自於能源體制能否深化改革，並且制訂出對外、對內策略一致的能源戰略，以因應中國未來的石油需求以及消減國際社會的疑慮。The new facet of global oil politics and China’s surging oil demand have forced the Chinese government and state-owned enterprises to secure foreign oil supplies and to implement energy efficiency. However, systemic level or state-centered theories have provided limited theoretic orientation to explain China’s state behaviors and foreign behavior. It is essential to explore China’s energy institution and energy strategy behind its quest for oil security. That is, China’s foreign strategy should be put into broader context of China’s institutional evolution and domestic/foreign energy policy-making process. This research applies historical institutionalism to look at history evolution of China’s energy institution and energy strategy (especially oil strategy). Chinese energy institution has experienced four main stages of institutional evolution since 1980s. The main themes of four stages have emphasized different administrative, institutional, and energy goals. Meanwhile, institutional critical junctures and feedbacks (formation and reproduction) also have existed in every stage. The first phrase (1980-1992) emphasized how to integrate market forces into China’s bureaucratic institution with socialist characteristics and the market oriented reforms faced several institutional challenges due to necessity of central planning; the second phrase (1993-1997) was characterized by slight and limited institutional restructuring within the energy sector because market force did not gain political support from the leadership. The Chinese government established both the State Energy Commission (SEC) (1980-82) and the Ministry of Energy (MOE) (1988-93) in the wake of acute energy shortages to re-centralize authority over the energy sector. However, neither institution could effectively coordinate and implement energy policy, partly because they could not overcome the vested interests in sectional industries. The third phrase (1998-2002) was characterized by radical institutional reforms on conglomerating SOEs and delimiting administrative power. The National Development and Reform Commission (NDRC) along with the Energy Bureau within it have taken over full governmental regulatory and public sector responsibility from SOEs. However, NDRC functions not as powerful as SOEs do. Therefore, the fourth phrase (2003 until now) then put attention on the establishment of a super-ministerial interagency, revivification of administrative power, and emphasis of foreign competitiveness. The establishment of State Energy Leading Group (SELG) aims at regaining strong central authority and to correcting turbulent oil strategies made on a base of institutional constraints. Above all, China’s institutional evolution is characteristic of state-regulated marketization, limited property right reforms, strategic preference, and departmentalism in China’s energy sector since 1980s. The institutional evolution has constrained China’s energy institution from planning a long-term national energy strategy. China’s energy sector continuously confirms institutional formation by the support of highest leadership and mainstream ideology, and confirms institutional reproduction between the directive and liberal forces, between the government and market forces. Meanwhile, international responses to China’s hunting behaviors are to play either a conductive role in impelling China’s institutional reforms and in adjusting its foreign behaviors. To prevent serious energy competition and to enhance international cooperation, China has shown its willingness to communicate with other nations on oil issues. However, China also needs to show its determination to implement domestic demand-side measures and a market approach instead of implementing protectionist “welcome-in” and aggressive “going out” policies. Ongoing institutional reforms still determines whether the China’s energy institution will ensure the country’s energy security. In the short term, the establishment of the central authority in the energy sector will improve departmental coordination and policy persistance. However, in the long term, China’s ongoing institional reforms need to integrate more market forces, proceed property right reforms, and reshape relationship between the government and market. Without deeper institutional reforms, energy bureaucrats and SOEs would be dragged into institutional process of formation and reproduction but gain limited results in meeting China’s oil security

EFECL: Feature encoding enhancement with contrastive learning for indoor 3D object detection

Abstract Good proposal initials are critical for 3D object detection applications. However, due to the significant geometry variation of indoor scenes, incomplete and noisy proposals are inevitable in most cases. Mining feature information among these “bad” proposals may mislead the detection. Contrastive learning provides a feasible way for representing proposals, which can align complete and incomplete/noisy proposals in feature space. The aligned feature space can help us build robust 3D representation even if bad proposals are given. Therefore, we devise a new contrast learning framework for indoor 3D object detection, called EFECL, that learns robust 3D representations by contrastive learning of proposals on two different levels. Specifically, we optimize both instance-level and category-level contrasts to align features by capturing instance-specific characteristics and semantic-aware common patterns. Furthermore, we propose an enhanced feature aggregation module to extract more general and informative features for contrastive learning. Evaluations on ScanNet V2 and SUN RGB-D benchmarks demonstrate the generalizability and effectiveness of our method, and our method can achieve 12.3% and 7.3% improvements on both datasets over the benchmark alternatives. The code and models are publicly available at https://github.com/YaraDuan/EFECL

Estimating anthropogenic heat from an urban rail transit station: A Case study of Qingsheng metro station, Guangzhou, China

Urban rail transit stations in hot and humid regions of South China release considerable amounts of anthropogenic heat (AH). However, the components of AH, including their calculation methods and temporal characteristics, have not been sufficiently investigated. In this study, the components of AH from Qingsheng metro station were calculated using a combined approach (i.e. the bottom-up inventory method and the comprehensive heat transfer coefficient method) based on statistical station operation data and the field measured meteorological data. Then, the hourly AH and its components were estimated. The results showed that QM and QT exhibited dual peaks, whereas QB and total AH exhibited a single peak during the operation period (06:00–24:00). The maximum values of AH at 12:00 were 35.15 W•m−2. Among the three components, QB contributed the greatest to AH, followed by QT and QM. A comparison of AH with the absorbed solar radiation by the horizontal envelope indicated that AH should be considered to be an important heat source in urban rail transit stations

Damage mechanism of conventional joints and proposal of a novel joint for hollow-core slab bridges

The prefabricated hollow-core slab bridge is a common bridge. In prefabricated hollow-core slab bridges, joints play an important role in connecting prefabricated slabs and ensuring the integrity of the bridge. However, as the service time of the bridge increases, conventional joints have a large number of typical diseases that affect the safety and durability of bridges. In this study, a three-dimensional finite element model of the entire construction phase is established to investigate the development difference of shrinkage and creep between joints and hollow-core slabs. The effects of vehicle load and temperature gradient on joints were analysed, the failure mechanism of joints was explored, and a novel joint was proposed. The results of a nonlinear analysis showed that the novel joint can effectively improve the mechanical performance of joints and cracks can be effectively controlled. Moreover, the novel joint solves the problem in that the conventional novel joint cannot be vibrated effectively

Comparison of Modified Mohr–Coulomb Model and Bai–Wierzbicki Model for Constructing 3D Ductile Fracture Envelope of AA6063

Abstract Ductile fracture of metal often occurs in the plastic forming process of parts. The establishment of ductile fracture criterion can effectively guide the selection of process parameters and avoid ductile fracture of parts during machining. The 3D ductile fracture envelope of AA6063-T6 was developed to predict and prevent its fracture. Smooth round bar tension tests were performed to characterize the flow stress, and a series of experiments were conducted to characterize the ductile fracture firstly, such as notched round bar tension tests, compression tests and torsion tests. These tests cover a wide range of stress triaxiality (ST) and Lode parameter (LP) to calibrate the ductile fracture criterion. Plasticity modeling was performed, and the predicted results were compared with corresponding experimental data to verify the plasticity model after these experiments. Then the relationship between ductile fracture strain and ST with LP was constructed using the modified Mohr–Coulomb (MMC) model and Bai-Wierzbicki (BW) model to develop the 3D ductile fracture envelope. Finally, two ductile damage models were proposed based on the 3D fracture envelope of AA6063. Through the comparison of the two models, it was found that BW model had better fitting effect, and the sum of squares of residual error of BW model was 0.9901. The two models had relatively large errors in predicting the fracture strain of SRB tensile test and torsion test, but both of the predicting error of both two models were within the acceptable range of 15%. In the process of finite element simulation, the evolution process of ductile fracture can be well simulated by the two models. However, BW model can predict the location of fracture more accurately than MMC model.http://deepblue.lib.umich.edu/bitstream/2027.42/173945/1/10033_2021_Article_549.pd

Quantitative Understanding of the Environmental Effect on B10 Copper Alloy Corrosion in Seawater

Corrosion in natural seawater is difficult to simulate in a laboratory due to the slow rate and complexity of the corrosion process which involves multiple influential factors. This paper aims to explore the quantitative effect of environmental factors on corrosion process and find the best experimental conditions which represent the actual environment and have the best acceleration effect. A new framework is followed in this paper which consists of three parts: design of experiments, outdoor and laboratory corrosion tests, and corrosion mechanism consistency confirmation. A L6(31 × 22) orthogonal experiment is designed in laboratory to study the effect of temperature, salinity, and dissolved oxygen on marine corrosion behavior of B10 copper alloy. In each test, H2O2 is added in seawater to accelerate the corrosion process. Outdoor exposure tests are also conducted in natural seawater. Results show that the corrosion process in laboratory and outdoor follows the same mechanism, in view of corrosion product and morphology, corrosion kinetics, as well as mechanical properties. With the help of quantitative analysis of the test results, a better acceleration condition can be designed

Effects of Total Dissolved Gas Supersaturation on the Survival of Juvenile <i>Procypris rabaudi</i> and Juvenile <i>Myxocyprinus asiaticus</i> at Varying Water Depth in a Natural River

Total dissolved gas (TDG) supersaturation, which can be caused by flood discharge, results in gas bubble disease (GBD) in fish and threatens their survival downstream of dams. TDG supersaturation has become a serious environmental problem in the Yangtze River. Few studies have evaluated the effect of TDG supersaturation on fish in natural rivers during periods of flood discharge. To estimate fish tolerance to TDG supersaturation under natural conditions, juvenile Myxocyprinus asiaticus and juvenile Procypris rabaudi were exposed to TDG-supersaturated water for 96 h at various depths (0–0.3 m, 0.3–1.3 m, 1.3–2.3 m and 0–2.3 m) during periods of flood discharge of Dagangshan hydropower station. The results showed that juvenile Procypris rabaudi and juvenile Myxocyprinus asiaticus exhibited obvious GBD signs. An increase in exposure time decreased survival probability of the two species. Deeper water depths can increase the tolerance of juvenile Procypris rabaudi to TDG supersaturation in natural rivers during periods of flood discharge while it cannot improve the survival of juvenile Myxocyprinus asiaticus. Compared with juvenile Myxocyprinus asiaticus, juvenile Procypris rabaudi showed weaker tolerance of TDG supersaturation in shallow water, and juvenile Procypris rabaudi were more vulnerable to TDG supersaturation than juvenile Myxocyprinus asiaticus even if the TDG level (116%) was low