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71.
Susan S. Gray Barbara J. Loud Carole P. Sokolowski 《Canadian Journal of Science, Mathematics, & Technology Education》2013,13(2):59-72
Abstract The ability to use and interpret algebraic variables as generalized numbers and changing quantities is fundamental to the learning of calculus. This study considers the use of variables in these advanced ways as a component of algebraic thinking. College introductory calculus students' (n = 174) written responses to algebra problems requiring the use and interpretation of variables as changing quantities were examined for evidence of algebraic and arithmetic thinking. A framework was developed to describe and categorize examples of algebraic, transitional, and arithmetic thinking reflected in these students' uses of variables. The extent to which students' responses showed evidence of algebraic or arithmetic thinking was quantified and related to their course grades. Only one third of the responses of these entering calculus students were identified as representative of algebraic thinking. This study extends previous research by showing that evidence of algebraic thinking in students' work was positively related to successful performance in calculus. 相似文献
72.
73.
Barbara Yersin Jonathan Maïm Fiorenzo Morini Daniel Thalmann 《The Visual computer》2008,24(10):859-870
Real-time crowd motion planning requires fast, realistic methods for path planning as well as obstacle avoidance. In a previous
work (Morini et al. in Cyberworlds International Conference, pp. 144–151, 2007), we introduced a hybrid architecture to handle real-time motion planning of thousands of pedestrians. In this article, we
present an extended version of our architecture, introducing two new features: an improved short-term collision avoidance
algorithm, and simple efficient group behavior for crowds. Our approach allows the use of several motion planning algorithms
of different precision for regions of varied interest. Pedestrian motion continuity is ensured when switching between such
algorithms. To assess our architecture, several performance tests have been conducted, as well as a subjective test demonstrating
the impact of using groups. Our results show that the architecture can plan motion in real time for several thousands of characters.
相似文献
Daniel ThalmannEmail: |
74.
Haoqiang Jin Barbara Chapman Lei Huang Dieter an Mey Thomas Reichstein 《International journal of parallel programming》2008,36(3):312-325
We describe a performance study of a multi-zone application benchmark implemented in several OpenMP approaches that exploit
multi-level parallelism and deal with unbalanced workload. The multi-zone application was derived from the well-known NAS
Parallel Benchmarks (NPB) suite that involves flow solvers on collections of loosely coupled discretization meshes. Parallel
versions of this application have been developed using the Subteam concept and Workqueuing model as extensions to the current
OpenMP. We examine the performance impact of these extensions to OpenMP and compare with hybrid and nested OpenMP approaches
on several large parallel systems. 相似文献
75.
Bill Moran Du Q. Huynh Xuezhi Wang Michael Edwards Andrew Harris Barbara F. La Scala 《Digital Signal Processing》2009,19(5):793-808
We describe here a method for the analysis of materials on a conveyor belt using the natural gamma spectra collected with a BGO (Bismuth Germanate) gamma ray detector. This detector collects gamma ray emissions from the Potassium (K), Uranium (U), and Thorium (Th) atoms in the materials. Based on these data, and using a Poisson model for the data generation, a statistical model is proposed and an approximate maximum likelihood (ML) technique based on the expectation-maximization (EM) algorithm is then used to estimate the amount of each of the three elements in the material. The statistical model is further refined to incorporate parameters of drift in the detector and an estimation technique for this is developed and tested against real data. The Cramér–Rao lower bounds for the estimators are calculated. 相似文献
76.
Compagnucci Ivan Corradini Flavio Fornari Fabrizio Polini Andrea Re Barbara Tiezzi Francesco 《Software and Systems Modeling》2023,22(3):969-1004
Software and Systems Modeling - The Internet of things has been adopted in several sectors both influencing how people work and enhancing organizations’ business processes. This resulted in... 相似文献
77.
Barbara Regine Armbruster 《Materials and Manufacturing Processes》2017,32(7-8):728-739
ABSTRACTThe gold work from the Western European Middle and Late Bronze Age (about 1500–700 BC) is characterized by solid ornaments and vessels. This article deals with manufacturing techniques of heavy gold jewelry by presenting a gold hoard found at Guînes, Pas-de-Calais, in Northern France, as a case study. In particular, three ornament types will be taken into consideration: (1) solid penannular neck and arm-rings, plain or with linear or geometric decoration; (2) flange-twisted ornaments that appear in different dimensions, as small as ear rings, as neck rings, up to the large size of a belt; (3) complex, composite ornaments. The technological aspects dealt with in this precious metal working context are manifold, including ingot and lost wax casting, hammering and bending of solid rods, the production of flange-twisted rods, chasing as decoration method, and finally joining techniques such as soldering, riveting and folding, and creasing. 相似文献
78.
Adherence rates to ferric citrate as compared to active control in patients with end stage kidney disease on dialysis 下载免费PDF全文
Diana Jalal Molly McFadden Jamie P. Dwyer Kausik Umanath Erwin Aguilar Yoram Yagil Barbara Greco Mohammed Sika Julia B. Lewis Tom Greene Simin Goral 《Hemodialysis international. International Symposium on Home Hemodialysis》2017,21(2):243-249
Introduction: Oral phosphate binders are the main stay of treatment of hyperphosphatemia. Adherence rates to ferric citrate, a recently approved phosphate binder, are unknown. Methods: We conducted a post‐hoc analysis to evaluate whether adherence rates were different for ferric citrate vs. active control in 412 subjects with end stage kidney disease (ESKD) who were randomized to ferric citrate vs. active control (sevelamer carbonate and/or calcium acetate). Adherence was defined as percent of actual number of pills taken to total number of pills prescribed. Findings: There were no significant differences in baseline characteristics including gender, race/ethnicity, and age between the ferric citrate and active control groups. Baseline phosphorus, calcium, and parathyroid hormone levels were similar. Mean (SD) adherence was 81.4% (17.4) and 81.7% (15.9) in the ferric citrate and active control groups, respectively (P = 0.88). Adherence remained similar between both groups after adjusting for gender, race/ethnicity, age, cardiovascular disease (CVD), and diabetic nephropathy (mean [95% CI]: 81.4% [78.2, 84.6] and 81.5% [77.7, 85.2] for ferric citrate and active control, respectively). Gender, race/ethnicity, age, and diagnosis of diabetic nephropathy did not influence adherence to the prescribed phosphate binder. Subjects with CVD had lower adherence rates to phosphate binder; this was significant only in the active control group. Discussion: Adherence rates to the phosphate binder, ferric citrate, were similar to adherence rates to active control. Similar adherence rates to ferric citrate are notable since tolerance to active control was an entry criteria and the study was open label. Gender, race/ethnicity, nor age influenced adherence. 相似文献
79.
Tersilla Virgili Arrigo Calzolari Inma Suárez López Alice Ruini Alessandra Catellani Barbara Vercelli Francesco Tassone 《Nano Research》2018,11(1):142-150
Formation of densely packed thin films of semiconductor nanocrystals is advantageous for the exploitation of their unique optoelectronic properties for real-world applications. Here we investigate the fundamental role of the structure of the bridging ligand on the optoelectronic properties of the resulting hybrid film. In particular, we considered hybrid films formed using the same CdSe nanocrystals and two organic ligands that have the same bidentate dithiocarbamate binding moiety, but differ in their bridging structures, one bridged by ethylene, the other by phenylene that exhibits conjugation. Based on the results of photo-excited carrier dynamics experiments combined with theoretical calculations on the electronic states of bridged CdSe layers, we show that only the phenylene-based ligand presents a strong hybridization of the molecular HOMO state with CdSe layers, that is a marker of formation of an effective bridge. We argue that this hybridization spread favors the hopping of photo-excited carriers between nanocrystals, which may explain the reported larger photo-currents in phenylene-based hybrid films than those observed in ethylene-based ones. 相似文献
80.
Computer systems increasingly carry out tasks in mixed networks, that is in group settings in which they interact both with other computer systems and with people. Participants in these heterogeneous human-computer groups vary in their capabilities, goals, and strategies; they may cooperate, collaborate, or compete. The presence of people in mixed networks raises challenges for the design and the evaluation of decision-making strategies for computer agents. This paper describes several new decision-making models that represent, learn and adapt to various social attributes that influence people's decision-making and presents a novel approach to evaluating such models. It identifies a range of social attributes in an open-network setting that influence people's decision-making and thus affect the performance of computer-agent strategies, and establishes the importance of learning and adaptation to the success of such strategies. The settings vary in the capabilities, goals, and strategies that people bring into their interactions. The studies deploy a configurable system called Colored Trails (CT) that generates a family of games. CT is an abstract, conceptually simple but highly versatile game in which players negotiate and exchange resources to enable them to achieve their individual or group goals. It provides a realistic analogue to multi-agent task domains, while not requiring extensive domain modeling. It is less abstract than payoff matrices, and people exhibit less strategic and more helpful behavior in CT than in the identical payoff matrix decision-making context. By not requiring extensive domain modeling, CT enables agent researchers to focus their attention on strategy design, and it provides an environment in which the influence of social factors can be better isolated and studied. 相似文献