References of "Li, Yongzhen"
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See detailSpread of hatch and delayed feed access affect post hatch performance of female broiler chicks up to day 5.
Wang, Y.; Li, Yongzhen ULg; Willems, E. et al

in Animal (2014)

It is not rare that newly hatched chicks remain without feed for about 24 to 48 h before they are placed on farms due to a series of logistic operations. Furthermore, the spread in hatching time can also ... [more ▼]

It is not rare that newly hatched chicks remain without feed for about 24 to 48 h before they are placed on farms due to a series of logistic operations. Furthermore, the spread in hatching time can also mount up to 30 to 48 h for late v. early hatchers. In other words, the practice is a complex combination of spread of hatch and delayed feed access. The present study was aimed to investigate the combined effects of hatching time with a delay in feed access of 48 h, starting from their hatch-time (biological age). When chicks had access to feed immediately after hatch, late hatchers had a higher feed intake and relative growth rate up to day 5 compared with their early hatched counterparts. Feed deprivation during the first 48 h resulted in retarded early growth rate, which was further aggravated by an impaired feed intake after refeeding. In addition, the differential effects of hatching time on relative growth rate and feed intake observed in immediately fed chicks were eliminated by the 48 h feed delay. The yolk utilization after hatch was faster for the late hatchers up to biological day 2 regardless of the feeding treatments. Hatching muscle glycogen content was higher in the late hatchers compared with that of their early counterparts at hatch and at biological day 2 independent of feeding treatment. Moreover, the liver glycogen content of the late hatchers was also higher at hatch. For the immediately fed chicks, the proportional breast muscle weight of the late hatchers was higher at biological day 2 and 5. For the starved chicks, on the other hand, this effect was only observed after they had access to feed (biological day 5). The different plasma T3 levels at hatch may have contributed to the different post hatch performance. It is concluded that the spread of hatch influenced post hatch performance, especially appetite and growth at least until day 5. Moreover, the delay in feed access interacted with the hatching time and caused adverse effects on the post hatch performance. [less ▲]

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See detailExtension of the DSM to welded H profile cross-sections
Rossi, Barbara ULg; Li, Yongzhen ULg

in Research and Applications in Structural Engineering, Mechanics and Computation (2013)

The objective of the paper is to assess the accuracy of current Direct Strength Method (DSM) equations applied to steel structural welded H shapes in axial compression. Commercialised hot-rolled H ... [more ▼]

The objective of the paper is to assess the accuracy of current Direct Strength Method (DSM) equations applied to steel structural welded H shapes in axial compression. Commercialised hot-rolled H sections covering IPE, HE, HD, HL, HP, W and UB profiles and made of three grades (235MPa, 355MPa and 460MPa) were treated in (Li & Rossi 2012). This analysis focuses on welded sections made of the same three grades, including sections characterized by local buckling with a significant post-buckling reserve. The finite element model is described. Then, the results of a parametric analysis using the finite element model are re-ported. The codified resistances are also compared to the numerical results. For each cross-section, the recently developed analytical expressions provided in (Seif & Schafer 2010) for hot-rolled profiles are used to cal-culate the elastic cross-section local buckling stress. A comparison with CUFSM results is also reported. Then, the possibility to use the concept of DSM for the design of structural welded steel shapes is discussed. [less ▲]

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See detailFinite element model for the extension of the direct strength method to hot-rolled profile cross-sections
Li, Yongzhen ULg; Rossi, Barbara ULg

in Proceedings of the 12th Nordic Steel Construction Conference (2012, September 05)

Abstract: In the present research, a geometrically and materially nonlinear analysis using the FE method has been conducted to evaluate the resistance of axially compressed hot-rolled H profile cross ... [more ▼]

Abstract: In the present research, a geometrically and materially nonlinear analysis using the FE method has been conducted to evaluate the resistance of axially compressed hot-rolled H profile cross-sections. The FE model was firstly duly verified against experimental data and then used to carry a parametric analysis. The goal of the analysis is to propose a new Direct Strength Method (DSM) strength curve intended for calculating the resistance of non-compact and slender hot-rolled H profile cross-sections. [less ▲]

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See detailPrediction of the cross-section capacity of hot-rolled profiles using the direct strength method and the continuous strength method
Li, Yongzhen ULg; Rossi, Barbara ULg

in Chan, S.L.; Shu, G.P. (Eds.) Proceedings of seventh International Conference on Advances in Steel Structures (2012, April)

Material yielding on one hand and local buckling on the other hand limit the cross-section capacity of steel structural members. Current structural design codes use the concept of cross-section ... [more ▼]

Material yielding on one hand and local buckling on the other hand limit the cross-section capacity of steel structural members. Current structural design codes use the concept of cross-section classification to determine the cross-section resistance of hot-rolled profiles. In this system, the Effective Width Method (EWM) is employed to account for local buckling effects for slender, class 4, cross-sections. Alternative design methods for treatment of local buckling in metallic cross-sections have been proposed, including the Direct Strength Method (DSM), developed for cold-formed steel structural profiles, and, recently, the Continuous Strength Method (CSM). The DSM is based on the assumption that the strength can be predicted from the ratio of the yield strength to the elastic critical load in conjunction with a strength curve for the entire cross-section. Thus it is essentially an extension of the use of column curves for global buckling, but with application to local buckling instability. The CSM is a deformation-based design approach which is based on a continuous relationship between cross-sectional slenderness and cross-section deformation capacity and a rational exploitation of strain hardening. This paper is focused on the evaluation of the cross-sectional resistance of hot-rolled structural profiles. Test data from literature experimental programmes have been gathered and analysed to compare the predictions from the DSM and CSM design approaches. [less ▲]

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See detailExtension of the Direct strength method to hot-rolled profiles cross-sections
Li, Yongzhen ULg; Rossi, Barbara ULg; Jaspart, Jean-Pierre ULg

in 6th European Conference on Steel and Composite Structures : Eurosteel 2011, Budapest 30 October - 2 September 2011 (2011, September)

Current metallic structural design codes use the concept of section classification for determining the section capacity of hot-rolled profiles. In this system, there exists a discontinuity between the ... [more ▼]

Current metallic structural design codes use the concept of section classification for determining the section capacity of hot-rolled profiles. In this system, there exists a discontinuity between the classes 2 and 3, while for the class 4, the effective width method (EWM) must be used to account for local buckling phenomenon. In order to overcome the complicate and time consuming EWM for evaluating the strength, the alternative Direct Strength Method (DSM) approach, developed only for cold-formed thin-walled members, has gained importance over the last few years. The DSM is premised on the assumption that the strength can be predicted from the yield strength to the elastic critical load ratio in conjunction with a strength curve. The DSM has been advanced for calculating the strength of compression members over the past decades and in this paper, the extension of DSM to hot-rolled profiles cross-sections is investigated. Firstly, the methods for calculating the cross-section resistance such as EWM, DSM, and the recent Continuous Strength Method (CSM) are reviewed; a short comparison is made and their domains of applicability are commented. Secondly, a numerical model carried out in the frame of this research is described. The model was built in ABAQUS and verified against test results of the “Semi-comp: Plastic member capacity of semi-compact steel sections - a more economic design” project, which was carried out earlier with the objective of improving the utilization of plasticity in rolled and welded sections with medium cross-section slenderness. On the basis of these premises, the final goal of the project is detailed: to derive a new formulation that would cover the whole field of section slenderness (present class 1 to class 4), which can be seen as an extension of the so-called DSM approach. [less ▲]

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See detailIntermittent thermal manipulations of broiler embryos during late incubation and their immediate effect on the embryonic development and hatching process.
Willemsen, H.; Li, Yongzhen ULg; Willems, E. et al

in Poultry science (2011), 90(6), 1302-12

Intermittent high (+3 degrees C) and low (-3 degrees C) temperature treatments for 4 h on embryonic day (E) 16, E17, and E18 showed differential effects on embryonic metabolism, without influencing ... [more ▼]

Intermittent high (+3 degrees C) and low (-3 degrees C) temperature treatments for 4 h on embryonic day (E) 16, E17, and E18 showed differential effects on embryonic metabolism, without influencing embryonic growth or hatchability. Embryos in the high-temperature group shifted to a more anaerobic metabolism, as indicated by a lower partial pressure of O(2) and a higher partial pressure of CO(2) in the air cell, lower blood pH, and higher lactic acid production. Three hours after the end of the high-temperature treatment, a decrease in metabolism was observed, as indicated by the lower partial pressure of CO(2) and higher partial pressure of O(2) in the air cell and increased plasma triglyceride levels. The embryos in the low-temperature group responded by temporarily slowing down their metabolism, especially the metabolism of carbohydrates and lipids, as indicated by altered air cell gases, a higher relative yolk weight, higher plasma triglyceride level, and higher liver glycogen level. Three hours after the end of the temperature treatment, the metabolism of embryos in the low-temperature treatment had increased to the level of the control temperature group. However, for both temperature treatments, during the hatching process, all the shortages and excesses created were restored to control levels, which would explain the lack of change in embryo growth and hatchability and the slight delay in the hatching process. These mild consequences of the intermittent temperature treatment indicate that the different metabolic shifts made by the embryos seem to be efficient in overcoming the challenges of the intermittent high- or low-temperature treatment during late incubation. [less ▲]

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See detailEffect of early feeding on intermediary metabolism of broiler chicks differing in hatching time
Debonne, M.; Witters, A.; Li, Yongzhen ULg et al

in EAAP series (2010)

[No abstract available]

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