499 research outputs found
Molecular anhydrobiology: Identifying molecules implicated in invertebrate anhydrobiosis
No full text
Dynamics of Network Formation Processes in the Co-Author Model
No full textThis article studies the dynamics in the formation processes of a mutual consent network in game theory setting: the Co-Author Model. In this article, a limited observation is applied and analytical results are derived. Then, 2 parameters are varied: the number of individuals in the network and the initial probability of the links in the network in its initial state. A simulation result shows a finding that is consistent with an analytical result for a state of equilibrium while it also shows different possible equilibria.Dynamics, Network, Game Theory, Model,Simulation, Equilibrium, Complexity
Isolated propeller aeroacoustics at positive and negative thrust Author links open overlay panel
No full textUsing propellers in negative thrust conditions can potentially result in many benefits, such as a steeper descent, a reduced landing run, reduced community noise, energy regeneration, etc. However, the aerodynamics and aeroacoustics of propellers in this regime are not well understood. This paper presents an aeroacoustic analysis of an isolated propeller operating in both positive and negative thrust conditions, using scale-resolved lattice-Boltzmann very large eddy simulations and the Ffowcs Williams & Hawkings analogy. The propeller was operated at a constant tip Mach number so that any differences in tonal noise between positive and negative thrust conditions were due to changes in blade loading. Results showed that the flow separation around the blades in the negative thrust case led to a 2 to 6 times higher standard deviation in integrated thrust compared to the positive thrust case. The blade loading in the negative thrust case shows the amplitude of fluctuations up to 18% for inboard sections and up to 30% near the blade tip compared to the time-averaged loads. The noise in the propeller plane is 10 dB higher in the positive thrust regime than in the negative thrust regime at a given absolute thrust level of
. The lower noise at negative thrust is caused by two factors: the lower magnitude of the negative torque compared to the positive torque at a given thrust level and the shift of the blade loading inboard in the negative thrust condition due to the stall of the blade tip. Along the propeller axis, the negative thrust regime has 13-15 dB higher noise because of the increased broadband noise generated by the flow separation. In the negative thrust case, the noise along the propeller axis (89 dB) and propeller plane (92 dB) are comparable. However, this is not the case for the propulsive case. The comparison of noise in the vicinity of the propeller plane showed that using the propellers in negative thrust conditions allows for a steeper and quieter descent compared to a conventional descent; as long as the magnitude of the negative torque produced is equal to or less than the torque required to operate the propeller in a conventional landing
Inferring object states and articulation modes from egocentric videos
No full textWe develop algorithms for understanding objects from the point of view of interacting with them. There are two key aspects to obtaining such an understanding. First, objects can occur in different states and we need features that are sensitive to such states. Second, different objects can be articulated in different ways and we need to understand how to correctly infer their modes of articulation. We propose self and weakly supervised techniques to obtain such an understanding of objects purely through observation of how humans interact with the world around them through their hands. Our experiments on the challenging EPIC- KITCHENS dataset show the merits of using human hands as a probe for understanding objects.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-05-01The student, Rishabh Goyal, accepted the attached license on 2021-04-27 at 12:26.The student, Rishabh Goyal, submitted this Thesis for approval on 2021-04-27 at 13:39.This Thesis was approved for publication on 2021-04-28 at 09:43.DSpace SAF Submission Ingestion Package generated from Vireo submission #16585 on 2021-09-16 at 17:06:08Made available in DSpace on 2021-09-17T02:34:49Z (GMT). No. of bitstreams: 2
GOYAL-THESIS-2021.pdf: 26378428 bytes, checksum: 5fb34e7c3f1a83a84f3c5ba07fefd80f (MD5)
LICENSE.txt: 4210 bytes, checksum: 37522f5c1ac72c7fb0aa7fa78a307c50 (MD5)
Previous issue date: 2021-04-28Embargo set by: Seth Robbins for item 118591
Lift date: 2023-09-17T02:34:57Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Onl
Aerodynamics and Far-field Noise Emissions of a Propeller in Positive and Negative Thrust Regimes at Non-zero Angles of Attack
No full textThis paper studies the effect of operation at non-zero angles of attack on the aerodynamic performance and far-field noise emissions of an isolated propeller operating at positive and negative thrust conditions. To achieve this, scale-resolved lattice-Boltzmann very large eddy simulations coupled with the Ffowcs Williams & Hawkings analogy have been used. The results show that when the propeller operates with a 10◦ angle of attack at the positive thrust condition, the blade loading increases on the advancing side and decreases on the retreating side, leading to a 9.6% increase in integrated thrust (when computed along the propeller axis) and a negligible increase (0.1%) in propeller efficiency. Conversely, at the negative thrust condition, the operation at 10 deg angle of attack results in a 7.9% decrease in thrust magnitude and an 11.1% reduction in energy-harvesting efficiency. In this condition, the positively cambered blade sections exhibit dynamic stall at the 10◦ angle of attack, resulting in broadband fluctuations of up to 10% of the mean loading. As a result of the opposite change in absolute blade loading in the negative thrust condition compared to the positive thrust condition at the 10◦ angle of attack, the change in the noise directivity is also the opposite. Whereas in the positive thrust case, the noise increases in the region from which the propeller is tilted away (i.e., below the propeller at a positive angle of attack), in the negative thrust case, it is the other way around. This study highlights the need to account for non-zero angles of attack in propeller design and optimization analyses
Recent trends in water-use optimization of surface irrigation systems in Australia
No full textKoech, RK ORCiD: 0000-0002-0563-6687The surface system has seen improvements in the recent past ranging from infrastructural upgrades or automation to changes in the management practices and regulatory regimes. Data presented have demonstrated that these improvements have contributed to better water use efficiency of the surface system. Past designs of automatic and real-time control systems have been excessively complex and costly, and hence no significant adoption is evident. A new, simple automatic real-time control system for furrow irrigation is described in this chapter. Field trials have demonstrated potential for water savings, and further development and commercialization of the system is underway
Small world: Narrow, wide, and long replication of Goyal, van der Leij and Moraga‐Gonzélez (JPE 2006) and a comparison of EconLit and Scopus
No full textI undertake a narrow, wide, and long replication of Goyal, van der Leij and Moraga‐Gonzélez (2006, https://doi.org/10.1086/500990). Using social network analysis, they show that the Economics profession gradually evolved into a small world. Small worlds (or small world networks) have unique information transmission capabilities. The trend is explained by the emergence of frequently publishing researchers with many distinct co‐authors. In a social network, they resemble stars. The original results are robust to the usage of (I) another software, (II) a recent version of the originally used data, and (III) another database and a more sophisticated author disambiguation
Small World: Narrow, Wide and Long replication of Goyal, van der Leij and Moraga-González (JPE 2006) and a Comparison of EconLit and Scopus
No full textI undertake a narrow, wide and long replication of Goyal, van der Leij and Moraga-González (Journal of Political Economy 2006; 114(2): 403–412). Using social network analysis they show that the Economics profession gradually evolved into a small world. Small worlds (or small world networks) have unique information transmission capabilities. The trend is explained by the emergence of frequently publishing researchers with many distinct co-authors. In a social network they resemble stars. The original results are robust to the usage of (I) another software, (II) a recent version of the originally used data, and (III) another database and a more sophisticated author disambiguation
Hip fracture risk assessment: Artificial neural network outperforms conditional logistic regression in an age- and sex-matched case control study
No full textCopyright @ 2013 Tseng et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.Background - Osteoporotic hip fractures with a significant morbidity and excess mortality among the elderly have imposed huge health and economic burdens on societies worldwide. In this age- and sex-matched case control study, we examined the risk factors of hip fractures and assessed the fracture risk by conditional logistic regression (CLR) and ensemble artificial neural network (ANN). The performances of these two classifiers were compared.
Methods - The study population consisted of 217 pairs (149 women and 68 men) of fractures and controls with an age older than 60 years. All the participants were interviewed with the same standardized questionnaire including questions on 66 risk factors in 12 categories. Univariate CLR analysis was initially conducted to examine the unadjusted odds ratio of all potential risk factors. The significant risk factors were then tested by multivariate analyses. For fracture risk assessment, the participants were randomly divided into modeling and testing datasets for 10-fold cross validation analyses. The predicting models built by CLR and ANN in modeling datasets were applied to testing datasets for generalization study. The performances, including discrimination and calibration, were compared with non-parametric Wilcoxon tests.
Results - In univariate CLR analyses, 16 variables achieved significant level, and six of them remained significant in multivariate analyses, including low T score, low BMI, low MMSE score, milk intake, walking difficulty, and significant fall at home. For discrimination, ANN outperformed CLR in both 16- and 6-variable analyses in modeling and testing datasets (p?<?0.005). For calibration, ANN outperformed CLR only in 16-variable analyses in modeling and testing datasets (p?=?0.013 and 0.047, respectively).
Conclusions - The risk factors of hip fracture are more personal than environmental. With adequate model construction, ANN may outperform CLR in both discrimination and calibration. ANN seems to have not been developed to its full potential and efforts should be made to improve its performance.National Health Research Institutes in Taiwa
- …
