Suspension system performance optimization with discrete design variables

Suspension systems on commercial vehicles have become an important feature meeting the requirements from costumers and legislation. The performance of the suspension system is often limited by available catalogue components. Additionally the suspension performance is restricted by the travel speed which highly influences the ride comfort. In this article a suspension system for an articulated dump truck is optimized in sense of reducing elapsed time for two specified duty cycles without violating a certain comfort threshold level. The comfort threshold level is here defined as a whole-body vibration level calculated by ISO 2631-1. A three-dimensional multibody dynamics simulation model is applied to evaluate the suspension performance. A non-gradient optimization routine is used to find the best possible combination of continuous and discrete design variables including the optimum operational speed without violating a set of side constraints. The result shows that the comfort level converges to the comfort threshold level. Thus it is shown that the operational speed and hence the operator input influences the ride comfort level. Three catalogue components are identified by the optimization routine together with a set of continuous design variables and two operational speeds one for each load case. Thus the work demonstrates handling of human factors in optimization of a mechanical system with discrete and continuous design variables.     

Estimation of forming limit diagrams by the use of the finite element method and Monte Carlo simulation

A stochastic finite element-based approach for forming limit calculations of sheets is proposed and evaluated. Material inhomogeneities are represented by spatial thickness variations of the sheet which are modelled by the use of random fields. The effects of changing the smoothness, wavelengths, amplitude and anisotropy of the field realisations on the forming limit diagram are investigated. Further, the effects of the patch size and plastic anisotropy on the forming limit diagram are studied. The assumed thickness variations result in a quite wide scatter band, and changes of the characteristics of the thickness field result in changes of the shape and variance of the forming limit diagram.     

Synthesis and structural studies of “branched” 2-linked trisaccharides related to h-type 2 blood group determinants

A series of fucosylated trisaccharides l-Fuc-(1→2)-ß-d-Gal-(1→4)-ß-X-OMe (1-6, X = d-GlcNAc, d-Qui (6-deoxy-Glc), d-Xyl) related to H type 2 blood group determinant have been synthesized both as their α- and ß- L-Fuc anomers together with the component disaccharide starting compounds (7-11). The conformational properties of the trisaccharides together with their parent disaccharides have been investigated by NMR spectroscopy (proton and carbon chemical shifts and proton NOEs) in combination with computer modeling using the Monte Carlo approach and the HSEA force field using the GEGOP program with the main focus on the α-linked fucose series. The series of compounds allow for the investigation of interaction between the sugar units in the—in principle—linear structures, which in practice behave as branched trisaccharides. The interaction between the terminal fucose unit and the unit at the reducing end has been probed by substitution of the bulky CH₂OH group with CH₃ and H substituents, respectively. Compounds with severe steric interactions can be identified by the non-additivity of their carbon chemical shifts and subsequently confirmed by the detailed conformational assessment by NOEs and computer modeling. The most severe contacts arise in the GlcNAc and Qui trisaccharide series, whereas the Xyl-containing trisaccharide derivatives only exhibit weak steric interaction as probed by the NMR parameters.     

Identification of Novel Fragments Binding to the PDZ1-2 Domain of PSD-95

Inhibition of PSD-95 has emerged as a promising strategy for the treatment of ischemic stroke, as shown with peptide-based compounds that target the PDZ domains of PSD-95. In contrast, developing potent and drug-like small molecules against the PSD-95 PDZ domains has so far been unsuccessful. Here, we explore the druggability of the PSD-95 PDZ1-2 domain and use fragment screening to investigate if this protein is prone to binding small molecules. We screened 2500 fragments by fluorescence polarization (FP) and validated the hits by surface plasmon resonance (SPR), including an inhibition counter-test, and found four promising fragments. Three ligand efficient fragments were shown by ¹H,¹⁵N HSQC NMR to bind in the small hydrophobic P⁰ pockets of PDZ1-2, and one of them underwent structure-activity relationship (SAR) studies. Overall, we demonstrate that fragment screening can successfully be applied to PDZ1-2 of PSD-95 and disclose novel fragments that can serve as starting points for optimization towards small-molecule PDZ domain inhibitors.     

Robustness study on the behaviour of top-hat thin-walled high-strength steel sections subjected to axial crushing

A robustness study on the behaviour of top-hat thin-walled high-strength steel sections from different batches subjected to dynamic axial crushing has been performed. The robustness was investigated by considering 25 components produced from five different material batches. The variation of material properties within and between the batches was characterised by use of tensile tests. A 3D scanner was used in order to study the geometric imperfections of the profiles. The components were crushed in a kicking machine at an impact velocity of 10 m/s with an impacting mass of 985 kg. Fracture was observed in all the components, but the extent of fracture varied from batch to batch and seemed to be positively correlated to the material strength and negatively correlated to the material ductility. The mean force varied significantly within each batch, while the variation in the batch mean of the mean force was relatively small compared to the variations in the batch means of the material strength and thickness.     

Effects of particle characteristics on bulk properties of norwegiata fish meals

Three categories of Norwegian fish meats with different particle size, shape and particle surface stickiness characteristics were exposed to angle of repose and bulk density tests. The results presented indicate that the angle of repose increases with decreasing particle size, increasing amounts of fibrous particles in the powder and increasing particle surface stickiness. The bulk density, on the other hand, did not correlate with the particle size in the range considered, but increased with decreasing amounts of fibrous materials and decreasing surface stickiness.     

Experimental determination of mushy zone permeability in aluminum-copper alloys with equiaxed microstructures

An experimental apparatus for measuring the mushy zone permeability of aluminum-copper alloys with equiaxed microstructures has been constructed. Permeabilities have been measured for high solid fractions (0.68 to 0.91) and different dendrite morphologies. Microstructure characterizations on both the interdendritic and extradendritic length scales have been performed on the samples. The results are in fairly good agreement with the predictions of the Kozeny-Carman relation and with more recent theory that takes flow partitioning between interdendritic and extradendritic regions into account.     

Optimisation of the broiler production supply chain

In this paper, we propose a mixed integer programming (MIP) model for the Chicken Flock Sizing, Allocation and Scheduling Problem (CFSASP), which is an important planning problem in the broiler production supply chain. To solve the CFSASP efficiently, two variants of rolling horizon heuristics (RHHs) have been developed and applied on the case of a Norwegian broiler production company. Computational results show that the RHHs successfully obtain high-quality solutions within a reasonable time. The value of optimisation is verified through comparison with the case company's plans, where the solutions from optimisation outperforms the current solutions. Sensitivity analyses are also conducted to provide managerial insights regarding certain strategic decisions, such as how many and which days to use for hatching of chickens. Due to the promising results, the case company is now implementing an optimisation-based decision support system based on the MIP model and solution methods shown in this paper.     

Modelling of tubes subjected to axial crushing

In the present study, the influence of element type and formulation is investigated in finite element analyses of aluminium profiles subjected to axial crushing. It is shown that solid element-based simulations give predictions in better agreement with experiments both with respect to energy dissipation and folding pattern, while plane stress shell elements markedly underestimate the energy dissipation. It is further found that shell elements with thickness stretch give dissipated energies in better agreement with those obtained in simulations with solid elements.