1,722,108 research outputs found
Structure-borne sound transmission on frameworks of beams
No full textMany engineering structures are built from frameworks of beams, particularly lightweight structures. For the purpose of noise control from airborne and structure-borne sources, it is useful to be able to predict vibration transmission across these frameworks. This thesis investigates the potential use of Advanced Statistical Energy Analysis (ASEA) to predict structure-borne sound transmission when the beams support multiple wave types due to wave conversion at the junction. In contrast to Statistical Energy Analysis (SEA), ASEA is able to account for high propagation losses and indirect coupling through the use of ray tracing.
SEA and ASEA were validated through comparison with measurements and numerical experiments with Finite Element Methods (FEM). When each beam supports at least two local modes for each wave type in the frequency band of interest and the modal overlap factor is at least 0.1, FEM and measurement data tend to have average values which form smooth curves such as those predicted by SEA and ASEA. It was shown that SEA and ASEA models could incorporate Euler-Bernoulli and Timoshenko theory by changing over from Euler-Bernoulli to Timoshenko group velocity when calculating the coupling loss factors. However, comparisons with measurements were not conclusive although there were indications that a suitable crossover frequency could be when Timoshenko and Euler-Bernoulli group velocities differ by at least 26%.
Agreement between FEM and ASEA indicates that it is appropriate to ignore phase effects in the ray tracing approach used with ASEA. This was particularly noteworthy for the three-bay and five-bay truss beams as these were perfectly periodic for which phase effects could be important. Results for an L-junction, a rectangular beam frame and a five-bay truss with relatively long beams and relatively high internal loss factors demonstrated that ASEA was able to incorporate high propagation losses. This was not possible with SEA. For a three-bay truss beam with relatively short beams ASEA showed close agreement with FEM and measurements confirming that there was significant indirect coupling rather than high propagation losses. There are indications from the five-bay truss beams that ASEA may no longer be accurate in predicting the response on beams that are at least three structural junctions away from the source beam, particularly when ASEA predicts high propagation losses on the receiving beam
Structure-borne sound transmission on frameworks of beams
No full textMany engineering structures are built from frameworks of beams, particularly lightweight structures. For the purpose of noise control from airborne and structure-borne sources, it is useful to be able to predict vibration transmission across these frameworks. This thesis investigates the potential use of Advanced Statistical Energy Analysis (ASEA) to predict structure-borne sound transmission when the beams support multiple wave types due to wave conversion at the junction. In contrast to Statistical Energy Analysis (SEA), ASEA is able to account for high propagation losses and indirect coupling through the use of ray tracing.
SEA and ASEA were validated through comparison with measurements and numerical experiments with Finite Element Methods (FEM). When each beam supports at least two local modes for each wave type in the frequency band of interest and the modal overlap factor is at least 0.1, FEM and measurement data tend to have average values which form smooth curves such as those predicted by SEA and ASEA. It was shown that SEA and ASEA models could incorporate Euler-Bernoulli and Timoshenko theory by changing over from Euler-Bernoulli to Timoshenko group velocity when calculating the coupling loss factors. However, comparisons with measurements were not conclusive although there were indications that a suitable crossover frequency could be when Timoshenko and Euler-Bernoulli group velocities differ by at least 26%.
Agreement between FEM and ASEA indicates that it is appropriate to ignore phase effects in the ray tracing approach used with ASEA. This was particularly noteworthy for the three-bay and five-bay truss beams as these were perfectly periodic for which phase effects could be important. Results for an L-junction, a rectangular beam frame and a five-bay truss with relatively long beams and relatively high internal loss factors demonstrated that ASEA was able to incorporate high propagation losses. This was not possible with SEA. For a three-bay truss beam with relatively short beams ASEA showed close agreement with FEM and measurements confirming that there was significant indirect coupling rather than high propagation losses. There are indications from the five-bay truss beams that ASEA may no longer be accurate in predicting the response on beams that are at least three structural junctions away from the source beam, particularly when ASEA predicts high propagation losses on the receiving beam
A taxonomic review of Oberthueria Kirby, 1892 (Lepidoptera, Bombycidae: Oberthuerinae) with description of three new species
No full textZolotuhin, Vadim V., Wang, Xing (2013): A taxonomic review of Oberthueria Kirby, 1892 (Lepidoptera, Bombycidae: Oberthuerinae) with description of three new species. Zootaxa 3693 (4): 465-478, DOI: 10.11646/zootaxa.3693.4.
Notes on the genus Prismosticta (Lepidoptera, Bombycidae) with description of a new species from China
No full textWang, Xing, Huang, Guo-Hua, Wang, Min (2011): Notes on the genus Prismosticta (Lepidoptera, Bombycidae) with description of a new species from China. Zootaxa 2895: 65-68, DOI: 10.5281/zenodo.20687
Some aspects of empirical likelihood
No full textChapter 1 is a non technical introduction to the thesis. In chapter 2, Basics of Large Deviation Theory, we illustrate the basic idea of large deviation theory and briefly review the history of its development. As a preparation, some of the important theorems which we will employ in the following chapters are also introduced.In chapter 3, Asymptotic Optimality of Empirical Likelihood Tests With Weakly Dependent Data, we extend the result of Kitamura (2001) to stationary mixing data. The key thing inproving the large deviation optimality is that the empirical measure of the independently and identically distributed data will obey the large deviation principal (LDP) with rate function equal to the relative entropy, but in general the large deviation performance of empirical measure of dependent data is complicated. In this chapter we add S-mixing condition to the stationary process and we show that the rate function of the LDP of S-mixing process is indeed equal to the relative entropy, and then asymptotic optimality follows from the large deviation inequality.In chapter 4, Large Deviations of Empirical Likelihood with Nuisance Parameters, we discuss the asymptotic efficiency of empirical likelihood in the presence of nuisance parameters combined with augmented moment conditions. We show that in the presence of nuisance parameters, the asymptotic efficiency of the empirical likelihood estimator of the parameter of interest will increase by adding more moment conditions, in the sense of the positive semidefiniteness of the difference of information matrices. As a by-product, we point out a necessary condition for the asymptotic efficiency to be increased when more moment condition are added. We also derive asymptotic lower bounds of the minimax risk functions for the estimator of the parameter of interest, and we show that the empirical likelihood estimator can achieve this bound.In chapter 5, Empirical Likelihood Estimation of Auction Models via Simulated Moment Conditions, we apply empirical likelihood estimation to the simplest first-price sealed bid auction model with independent private values. Through estimation of the parameter in the distribution function of bidders’ private values we consider a potential problem in the EL inference when the moment condition is not in an explicit form and hard to compute, or even not continuous in the parameter of interest. We deal with this issue following the method of simulated moment through importance sampling. We demonstrate the convergence of the empirical likelihood estimator from the simulated moment condition, and found that the asymptotic variance is larger than usual which is disturbed by simulation
Revision of the subgenus Scymnus (Parapullus) Yang from China (Coleoptera: Coccinellidae)
No full textChen, Xiao-Sheng, Ren, Shun-Xiang, Wang, Xing-Min (2012): Revision of the subgenus Scymnus (Parapullus) Yang from China (Coleoptera: Coccinellidae). Zootaxa 3174: 22-34, DOI: 10.5281/zenodo.27989
An optimal sparse sensing approach for scanning point selection and response reconstruction in full field structural vibration testing
No full textNon-contact vibration measurements, such as 3D scanning laser Doppler vibrometry (3D SLDV), are becoming more prevalent in testing next-generation lightweight aerospace structures. This approach reduces the impact of attached sensors and improves measurement reliability. Acquiring precise measurement data for the whole area is feasible, albeit it would demand a considerable amount of time and storage space for testing. The concept of compressed sensing has been recently approved as an effective way to exploit signal sparsity and achieve full response reconstruction with very few measurements. The objective of this work is to enhance the efficiency of non-contact vibration testing by utilizing the state-of-the-art compressive sensing approach. In contrast to conventional sensor placement methods that rely on effective independence, modal kinetic energy, or modal assurance criterion matrix as targets, this paper proposes a novel sensor placement methodology from the perspective of dynamic response reconstruction. The scanning points are chosen with a minimal number to reduce testing time and are well-placed such that full-field vibration responses of the test structure can be reconstructed accurately. This allows for the spatially-detailed vibration responses to be obtained efficiently and accurately with optimal sparse sensing placement and effective response reconstruction through ℓ
1 algorithm. Two case studies will be presented in this work to demonstrate and validate the methodology. The first case study is focused on a simplified cantilever beam using the numerical data from the FE analysis to demonstrate the methodology. The second case study is focused on using 3D SLDV experimental testing data from a full-scale industrial fan blade. Based on the results, it is evident that the proposed approach can significantly decrease the scanning points required for a full-field dynamic response reconstruction during full-field vibration testing.</p
FIGURE 1. Neopseustis archiphenax from Yintiaoling. HAUHL077900-077902. A–B in A new record family Neopseustidae (Insecta: Lepidoptera) from Chongqing of China, with the first description of the Neopseustis archiphenax female adult
No full textFIGURE 1. Neopseustis archiphenax from Yintiaoling. HAUHL077900-077902. A–B. male; C. female; D. male at rest. Scales bar: 5 mmPublished as part of Lv, Jun-Xian, Wang, Xing & Huang, Guo-Hua, 2023, A new record family Neopseustidae (Insecta: Lepidoptera) from Chongqing of China, with the first description of the Neopseustis archiphenax female adult, pp. 170-177 in Zootaxa 5257 (1) on page 172, DOI: 10.11646/zootaxa.5257.1.13, http://zenodo.org/record/776573
Prismosticta regalis Zolotuhin & Witt 2009
No full textPrismosticta regalis Zolotuhin & Witt, 2009 Prismosticta regalis Zolotuhin & Witt, 2009, Entomofauna 16: 252. Type locality: Fujian, China. Externally, this species is similar to P. tiretta, but can be distinguished from the latter by mesial gnathos distinctly swelling with heavy spinulate, medial part of the valva with a robust pyramide-like appendix, sacculus with a narrow and long toothed process directed dorsal margin. Distributed in China (Guangdong, Hainan, Fujian), Vietnam.Published as part of Wang, Xing, Huang, Guo-Hua & Wang, Min, 2011, Notes on the genus Prismosticta (Lepidoptera, Bombycidae) with description of a new species from China, pp. 65-68 in Zootaxa 2895 on page 67, DOI: 10.5281/zenodo.20687
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