Effects of roll crossing on the rolling process in four-high mills

Roll crossing can be utilized as a method for profile and flatness control in a rolling mill. The estimation of the profile adjusting range by calculating the elastic roll-gap deflection reveals that roll crossing has a similar effect on the profile as positive bending. Under the assumptions made in the calculations roll crossing is an effective method as profile and crown actuator. Furthermore the effect of roll crossing on the flatness is qualitatively confirmed by rolling trials. Beyond the investigation of the effectiveness of roll crossing as profile and flatness actuator a 3-dimensional finite element simulation of the material flow in the roll gap was done. The results of these simulations, which were confirmed by rolling trials as well, showed that the rolled specimen warps out of the passline due to the crossing of the work rolls whereas the influence of roll crossing on the distribution of local plastomechanical values is negligible. Force components in axial direction are induced by crossing the rolls, which have to be compensated by additional bearings. For the determination of the amount of axial forces rolling trials on a laboratory four-high mill were carried out.     

Minimally invasive osteosynthesis of fractures of the tibial head

The role of closed reduction techniques in tibial plateau fractures was evaluated retrospectively in a group of 33 patients. The patients had mainly B fractures (AO classification) and were treated by the arthroscopic reduction technique (n = 10) or by reduction under fluoroscopic control (n = 23) and transcutaneous screw fixation. The 21 patients with an average follow-up of 34 months (minimum 1 year) were reviewed. Using clinical and radiological criteria, 19 results were considered excellent to good. One patient with a residual deformity was revised with a total knee and 1 patient with an anatomical result had arthritic pain in the knee operated on. Arthroscopic reduction had no advantages over reduction under fluoroscopic control in this study. The specific value of the technically demanding endoscopic procedure should be questioned, as percutaneous reduction under fluoroscopic control may achieve comparable results in the majority of these cases.     

Automated estimation of white Gaussian noise level in a spectrum with or without spike noise using a spectral shifting technique

Various tasks, for example, the determination of signal-to-noise ratios, require the estimation of noise levels in a spectrum. This is generally accomplished by calculating the standard deviation of manually chosen points in a region of the spectrum that has a flat baseline and is otherwise devoid of artifacts and signal peaks. However, an automated procedure has the advantage of being faster and operator-independent. In principle, automated noise estimation in a single spectrum can be carried out by taking that spectrum, shifting a copy thereof by one channel, and subtracting the shifted spectrum from the original spectrum. This leads to an addition of independent noise and a reduction of slowly varying features such as baselines and signal peaks; hence, noise can be more readily determined from the difference spectrum. We demonstrate this technique and a spike-discrimination variant on white Gaussian noise, in the presence and absence of spike noise, and show that highly accurate results can be obtained on a series of simulated Raman spectra and consistent results obtained on real-world Raman spectra. Furthermore, the method can be easily adapted to accommodate heteroscedastic noise.     

Increase of process reliability in the micro-machining processes EDM-milling and laser ablation using on-machine sensors

In micro production micro electric discharge machining (μEDM) and laser ablation are two established manufacturing methods. Due to the thermal material removal mechanism there are some challenges to provide the needed process reliability. In both cases it is important to ensure a precise manufacturing process by the correct positioning of the tool, e.g. the laser spot, relative to the work piece and the measurement and elimination of geometrical deviations.Using the EDM-milling process to manufacture small cavities a deviation of the manufactured depth and a waviness of the surface may appear if the compensation of the tool wear does not work correctly. A confocal white-light sensor can be used to measure the surface of the machined cavity after the EDM process. An on-machine system provides the possibility to rework the work piece without unclamping it. Combining these two procedures in an automatic working quality loop the accuracy of the manufactured depth can be improved down to a maximum deviation of less than 2 μm. Regarding the laser ablation process using ultra short pulsed Nd:YAG lasers problems arise if the focal plane is not on the surface of the work piece. Due to the manufacturing in layers occurring deviations in the surface remain until the end of the machining process. In this work an acoustical sensor is used to provide a correctly adjusted focal plane at the beginning of the first manufacturing step. Acoustic emissions are detected during the ablation process. A signal analysis of the airborne sound spectrum emitted by the process enables specific conclusions about the focal position of the laser beam. Based on this correlation an acoustic focus positioning is built up and tested on a ceramic work piece. The focal plane can then be adjusted automatically before the ablation.     

The influence of vacuum impregnation on the fortification of apple parenchyma with quercetin derivatives in combination with pore structures X-ray analysis

The study aim was to investigate the vacuum impregnation (VI) technique for apple enrichment with quercetin glycosides from apple peel. Beside the determination of the quercetin content, structural effects on the apple parenchyma were analyzed by computerized microtomography (μCT). VI was an efficient method to enrich apples with quercetin derivatives which was affected by the apple cultivar, the vacuum pressure, the soluble solid concentration (SSC) and the viscosity of VI solution. After VI of 13 apple cultivars the quercetin content varied between 368 and 604 μg/g dry mass and correlated with the firmness of the native apple and the increased apple weight. The use of low SSC solution resulted in increased quercetin enrichment in contrast to apple pectin solutions with elevated viscosity. The μCT analyses demonstrate that VI was more effective in the inner apple sections than in the outer parts. The study indicates that differences of pore size and microstructure within the apple cortex substantially affected the enrichment process.     

The microecological effect of human milk

With mother's milk, in the colon a buffer system round pH 5 is dominating which consists of short chain organic acids and the corresponding anions. Thus, the activity of the microbial metabolism is retarded. The degradation of lactose remains maintained down to the faeces. With cow's milk, a neutral buffer system on the basis of phosphate, bicarbonate, and protein degradation products causes a rapid lactose degradation already in the upper colon. Putrefactive metabolites thereby released and absorbed burden the infant's still immature detoxifying capacity.     

Lactose--a potential dietary fiber. The regulation of its microecologic effect in the intestinal tract. 3. Dietary fiber actions of lactose due to microbial activity]

The activity of the mucosal beta-galactosidase of caecum and colon is low in both germfree and conventional rats. beta-Galactosidase activity occurs also in the chymus of germfree rats. It increases after monoassociation and is higher in conventional than in germfree animals. Lactose entering caecum and colon acts like dietary fibre and is hydrolysed mainly by the intestinal flora. Aerobe lactobacilli and bacteroides predominate in the microflora of rat caecum and colon. A lactose-containing diet increases the total number of germs and stimulates the growth of bifidobacteria. After special diets, rich in lactose and low in protein and phosphate (e.g. human milk and similar formulae), the number of bacteroides and other putrefactive germs decreases. Moreover, a lactose-containing diet alters the metabolic activity of intestinal microorganisms (activity of microbial beta-galactosidase, acidification and lowering of ph in the chymus, production of hydrogen, proteolytic activity.) Lactose as dietary fibre decreases the nitrogen excretion in the urine and increases the N-excretion in the faeces of conventional rats.