10,436 research outputs found
New Inverse Kinematics Algorithms Combining Closed Form Solutions with Nonlinear Optimization for Highly Redundant Robotic Systems
No full textThis paper presents inverse position kinematics algorithms with real time capability for Justin, a robotic system with high redundancy and many degrees of freedom. The combination of closed form solutions for parts of the kinematic chain embedded in a nonlinear equation solver is shown to be advantageous. The algorithms are evaluated with the DLR service robot Justin both in simulation and reality. Calculation times of 1 ms are achieved, including various optimization criteria for redundancy resolution. In case only a single arm with 7 DoF is considered, fast calculation time of 250 s is reached. With inclusion of an iterative step, reachability can be shown in more than 99% of the calculations regardless of the initial guess. The problem of weighting in multi-criteria optimization problems remains, though in the chosen approach the tool tip position is never compromised by other criteria due to the partially closed form solution. The presented algorithm can be applied to inverse position kinematics for all manipulators with serial or tree structure and redundant joints in case closed form solutions are available for parts of the kinematic chain
Using performance assessment in secondary school mathematics: an empirical study in a Singapore classroom
No full textThis article reports an exploratory study on using performance assessment in mathematics instruction in a high-performing secondary school in Singapore. An intact mathematics class participated in the study, and received chapter-based performance tasks as intervention during regular mathematics lessons for about one and a half school years. The performance tasks used included authentic and/or open-ended tasks. The students’ academic achievements and attitudes in mathematics were compared with a comparison class that did not receive the intervention. Both quantitative and qualitative data were collected, mainly through questionnaire surveys, performance task tests, conventional school exams, and interviews with students and teachers. The results suggest that the students receiving the intervention performed significantly better than their counterparts in solving conventional exam problems, and in general they also showed more positive changes in attitudes towards mathematics and mathematics learning. The students from the experimental class also expressed positive views about the benefits of using performance tasks in promoting their ability in higher order thinking, though no statistically significant difference was detected between the two classes of students in solving unconventional tasks before and after intervention. Overall, the results appear to support teachers’ using contextualised problems in real life situations and open-ended investigations in students’ learning of mathematic
S3_File._STARD-2015-checklist – Supplemental material for The diagnostic value of intracavitary electrocardiogram for verifying tip position of peripherally inserted central catheters in cancer patients: A retrospective multicenter study
No full textSupplemental material, S3_File._STARD-2015-checklist for The diagnostic value of intracavitary electrocardiogram for verifying tip position of peripherally inserted central catheters in cancer patients: A retrospective multicenter study by Ting Yu, Ligui Wu, Ling Yuan, Robert Dawson, Rongmei Li, Zhenzhu Qiu, Xiancui Wu, Ping Chen, Jing Qi, Yiqun Yang, Yuling Feng, Wei Xu, Weiwei Kong, Yang Chen, Shanping Li, Xiang Wu and Tingting Yan in The Journal of Vascular Access</p
Why hedge? Extent, nature, and determinants of derivative usage in U.S. municipalities
No full textUsing a hand-collected dataset of over 300 observations of large U.S. cities and counties, this paper investigates the extent, nature and determinants of derivatives usage in the municipal sector.Over half of our sample entities engage in derivative transactions and a vast majority of these transactions are intended to manage interest rate risk. Swaps, by far, are the most popular derivative instrument. In terms of the determinants of derivative usage,we find that the propensity to use derivatives as well as the extent of derivative usage is higher for municipalities that are larger and more financially constrained. We do not find growth to be related to municipal derivative usage. Contrary to suggestions made in the popular press, we fail to find managerial opportunism to be a significant factor in municipal derivative usage. We also find that more sophisticated managers of large municipalities and less sophisticated managers of small municipalities are more likely to engage in derivative transactions.Peer reviewe
A study on the reliability of consecutive k-Out-of-n: G systems based on Copula
No full textThe computation of reliability characteristics of a system that consists of dependent components is sometimes difficult especially when the type of dependence is not known. This article introduces the copula method to calculate the reliability of dependent consecutive k-out-of-n: G systems. The components in these systems are dependent on each other and the dependency may be either linear or nonlinear. The copula is a popular tool for modeling the dependence structure of data. It contains the information about the dependency structure of a vector of random variables and can capture nonlinear dependence. Based on the copula theory, the article analyzes the consecutive k-out-of-n: G systems and gets the reliability indexes. Finally, some numerical examples are presented to illustrate the results obtained in this article.Peer reviewe
S1_File._CONSORT-2010-Checklist – Supplemental material for The diagnostic value of intracavitary electrocardiogram for verifying tip position of peripherally inserted central catheters in cancer patients: A retrospective multicenter study
No full textSupplemental material, S1_File._CONSORT-2010-Checklist for The diagnostic value of intracavitary electrocardiogram for verifying tip position of peripherally inserted central catheters in cancer patients: A retrospective multicenter study by Ting Yu, Ligui Wu, Ling Yuan, Robert Dawson, Rongmei Li, Zhenzhu Qiu, Xiancui Wu, Ping Chen, Jing Qi, Yiqun Yang, Yuling Feng, Wei Xu, Weiwei Kong, Yang Chen, Shanping Li, Xiang Wu and Tingting Yan in The Journal of Vascular Access</p
S2_File._STROBE-statement – Supplemental material for The diagnostic value of intracavitary electrocardiogram for verifying tip position of peripherally inserted central catheters in cancer patients: A retrospective multicenter study
No full textSupplemental material, S2_File._STROBE-statement for The diagnostic value of intracavitary electrocardiogram for verifying tip position of peripherally inserted central catheters in cancer patients: A retrospective multicenter study by Ting Yu, Ligui Wu, Ling Yuan, Robert Dawson, Rongmei Li, Zhenzhu Qiu, Xiancui Wu, Ping Chen, Jing Qi, Yiqun Yang, Yuling Feng, Wei Xu, Weiwei Kong, Yang Chen, Shanping Li, Xiang Wu and Tingting Yan in The Journal of Vascular Access</p
Capital asset accounting policies under GASB Statement No. 34: Characteristics, antecedents, and implications
No full textIn this paper, we study the evolution of state and local governments’ capital asset accounting policies from the adoption of GASB Statement No. 34 through the fiscal year ending in 2016. We document substantial cross-sectional and time-series variation in the capitalization thresholds and estimated useful lives pertaining to major classes of capital assets, including buildings, equipment, improvements, and infrastructure assets. Diversity in capital asset accounting policies potentially diminishes the comparability of capital asset accounting information across governments and over time. We also discuss matters related to the implementation and ongoing use of the modified approach for reporting infrastructure assets. Our findings are useful to the GASB as well as to users of government financial reports.Peer reviewe
On the market timing and feedback effect of hedging: evidence from U.S. oil and gas producers
No full textPeer reviewe
S4_File._Numbers_of_initially_PICC_insertion_patients – Supplemental material for The diagnostic value of intracavitary electrocardiogram for verifying tip position of peripherally inserted central catheters in cancer patients: A retrospective multicenter study
No full textSupplemental material, S4_File._Numbers_of_initially_PICC_insertion_patients for The diagnostic value of intracavitary electrocardiogram for verifying tip position of peripherally inserted central catheters in cancer patients: A retrospective multicenter study by Ting Yu, Ligui Wu, Ling Yuan, Robert Dawson, Rongmei Li, Zhenzhu Qiu, Xiancui Wu, Ping Chen, Jing Qi, Yiqun Yang, Yuling Feng, Wei Xu, Weiwei Kong, Yang Chen, Shanping Li, Xiang Wu and Tingting Yan in The Journal of Vascular Access</p
- …
