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.     

Inclusions in commercial low and medium carbon ferromanganese

The microstructures of commercial low and medium carbon ferromanganese have been studied by optical microscopy and electron microprobe techniques. Element analysis and mapping have been performed on impurities in the matrix and nonmetallic inclusions present. The results show that the most common nonmetallic inclusion is managanese oxide, followed by complex compounds of managanese oxide, silicon oxide, and manganese sulfide. The different inclusions have been assessed according to the SS 111116 method. It follows that over 85 pct of the present nonmetallic inclusions are manganese oxides and that the amount of manganese oxide inclusions is inversely proportional to the carbon content in standard refined ferromanganese.     

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.     

Mechanisms of inclusion formation in low alloy steels deoxidised with titanium

Abstract

In the present investigation, the conditions for inclusion formation in two Ti deoxidised steels and one Al–Ca deoxidised steel have been examined by means of optical and electron microscopy, in combination with a thermo dynamic analysis of the phase relations involved. It is concluded that the Ti containing inclusions form as a result of a series of reactions occurring in the ladle, during solidification and in the solid state. The important solid state reaction products are MnS, TiN, and MnOTiO₂ . The presence of Mn rich compounds at the surface of the inclusions is consistent with the observation of a Mn depleted zone in the surrounding steel matrix. In contrast, the primary inclusions in the Al–Ca deoxidised steel are complex oxysulphides, which are thermodynamically more stable and can therefore form in the liquid state.     

Mechanisms of inclusion formation in Al−Ti−Si−Mn deoxidized steel weld metals

The present investigation is concerned with basic studies of the mechanisms of inclusion formation in submerged arc (SA), gas metal arc (GMA), and flux cored arc (FCA) steel weld metals. Theoretical models of deoxidation have been developed to establish a basis for quantitative predictions of important inclusion characteristics, such as volume fraction, size, and chemical composition from knowledge of weld metal chemistry and operating parameters. The relevance of these models has been tested against extensive inclusion data obtained from scanning electron microscope (SEM) and scanning transmission electron microscope (STEM) examinations of a large number of experimental welds containing various contents of aluminum, titanium, silicon, manganese, and oxygen.     

Acute erosions of the gastric mucosa in burned rats: effect of sucralfate

Endometriosis remains a significant cause of pain and ill health for women and is a significant factor in reducing quality of life for women. The ability of desquamated endometrium to attach and implant within the peritoneal cavity is dependent upon its ability to establish and maintain an adequate blood supply. New vascularization is therefore a key part in the progression of endometriosis. Increased angiogenic activity is present in the peritoneal cavity of patients who suffer from the disease and more recently the potent angiogenic growth factor VEGF has been shown to be increased in the peritoneal fluid in patients with this disease. Whilst the desquamated endometrium itself under the influence of hypoxia further to retrograde menstruation is a likely rich source of VEGF, activated peritoneal fluid macrophages and infiltrating macrophages are also a rich source of this angiogenic growth factor. Surprisingly, steroidal regulation of macrophage expression of VEGF also appears to be a feature of this disease.     

水泥磨用大功率(2800kW)行星齿轮减速器的研制

目前，国内水泥行业磨机主传动多数采用分流定轴齿轮减速器，但体积大，效率低。体积小，效率高而功率大于2500kW的行星齿轮减速器多为进口，价格昂贵，且备品、备件、维护困难。本机为目前国内功率最大的用于水泥磨的行星齿轮减速器，其外形尺寸、重量等指标与国外产品基本相同，但价格约为进口的l／3。     

Factors affecting initiation of pitting corrosion in super martensitic stainless steel weldments

Abstract

In the present investigation optical microscopy, in combination with sputtered neutral mass spectrometry (SNMS), has been used to examine the conditions for initiation of pitting corrosion in the heat affected zone (HAZ) of two super martensitic (SM) stainless steel weldments. It is shown that the corrosion resistance depends mainly on the nature of the surface oxide, as determined by the oxygen potential in the shielding gas and the HAZ temperature–time relationship, and less strongly on the underlying microstructure. In the absence of H₂S the initiation is associated with spalling of the iron enriched chromium oxide within a narrow region approximately 6 mm from the fusion line, where the contaminated oxide layer is thinnest. As H₂S is introduced, the region close to the fusion boundary becomes susceptible to localised corrosion because of the more extensive metal oxidation. Thus, the high temperature oxidation and iron oxide scale formation accompanying the welding operation appear to be the main factors affecting pitting corrosion initiation in SM stainless steel weldments.