Steady-state modelling of extrusion cooking employing response surface methodology

Extrusion cooking has been approached from the point of view of continuous screw reactor technology, applying a heuristic hypothesis to changes in biopolymer aggregate states. Engineering design variables, the nature of basic biopolymer reactions, mass-machine interactions, and problems in the modelling of product quality in extrusion cooking are discussed. Response surface methodology (RSM) and its applications are discussed in detail including its significance and limitations in the study of complicated experimental situations.     

On commutative DT0L systems

Restricted versions of DT0L systems, so-called commutative DT0L systems, are considered. In these systems the length of a word derived is independent of the order of tables used. It turns out that many interesting length sets or languages, such as the set of composite numbers, are generated by these systems. Moreover, this approach makes it possible to give new (and slightly generalized) proofs for some undecidability results concerning DT0L functions.     

Combined blowing with three ‐ hole lance in a sidewall blowing converter

Traditionally, in stainless steelmaking converters, oxygen has been blown by a one‐hole lance (1 HL) and sidewall tuyères. In order to reduce the tap‐to‐tap time, the multi‐hole lance has been used for oxygen blowing. The aim of this work was to develop blowing practise for a multi‐hole lance to reduce the tap‐to‐tap time and minimise metal splashing and spitting in the sidewall blowing converter (chromium converter). In the chromium converter the chemical energy of liquid ferrochrome (which contains 4 % silicon and 7 % carbon) is utilised for scrap melting by oxidising the silicon and the part of carbon. The research has been made by a dynamically scaled water model and full‐scale converter. Used parameters were the gas flowrate from sidewall tuyères and lance, lance height, charge weight and position of multi‐hole lance. Splashing has been measured during blowing from walls (splashing) and mouth of the converter model (spitting). The model tests indicated less splashing and spitting by the three‐hole lance (3 HL) than traditional 1 HL. The 1 HL caused strong skulling of the converter cone. By 3 HL blowing the position of the lance has a remarkable effect on the direction and the amount of splashing and lance life. Because of hot metal‐slag splashes, the life time of the 3 HL was halved by position 1 (compared to 1 HL). With the lance position 2 the splashing decreased by approx. 50% in model tests and lance life time increased by ~ 50% (compared to 1 HL) in the full‐scale converter. The model agreed well with the full‐scale converter. According to the process tests, the nominal productivity of the chromium converter has increased 15 % and depending on the refining practise and the silicon content of ferrochromium the lining life has increased 20 ‐ 30 %. In the future the multi‐hole lance will be tested in the AOD vessel.     

Logic of the image

In this the Centennial Year of Alvar Aalto's birth a plethora of events and writings have emanated from sources independent of his origins. Juhani Pallasmaa has lived and worked in the cultural ambience of a world figure in a small country. In reviewing the inheritance of any architect who in his early career prompted a semi-official meeting of the Finnish Architects' Association to 'stop the daredevil before he could cause irreparable harm to the reputation of the esteemed profession' and now is held in such awe that sober critical evaluation has become seriously compromised, he provides fresh insight into Aalto's 'synthetic and inclusive architecture' as landscape, as typology, as tactile experience, as rational structure, as episodic sequence, as 'haptic experience'.     

Occurrence and destruction of PAHs,PCBs, CIPhs,CIBzs, and PCDD/Fs in ash from gasification of straw

Two experiments were performed with an atmospheric circulating fluidized bed gasifier (ACFBG), the first with pelletized straw and the second with loose straw, to investigate the occurrence of polycyclic aromatic hydrocarbons (PAHs), chlorophenols (CIPhs), polychlorinated biphenyls (PCBs), polychlorinated benzenes (ClBzs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) in the bottom ash and fly ash formed during gasification. Only PAHs were present in large amounts, and only in the fly ash, ranging from 300 to 555 mg/kg ash in the tests with pelletized straw and from 73 to 118 mg/kg ash in those with loose straw. These amounts are so high that environmentally safe disposal or reuse of the ash would be difficult, so the development of a technique to handle the problem was included in the project. The method investigated was to burn the fly ash in a circulating fluidized bed (CFB) boiler in order to destroy the PAHs. This worked surprisingly well, eliminating 99% of the PAHs, without any further formation of the other harmful organic compounds analyzed. Thus, this method could actually be useful in practice. Especially the fact that the formation of PCDD/Fs was minimal during gasification and further treatment of the ash in the CFB boiler makes the gasification technique highly competitive relative to conventional combustion methods.     

A Simulation Model for the Control of beta‐Glucanase Activity and beta‐Glucan Degradation During Germination in Malting

A dynamic model was developed that describes the formation of β‐glucanase and the degradation of β‐glucans at different temperatures and grain moistures during the germination of malting barley. The process was analysed by simulations and by solving an optimal control problem for maximising the β‐glucanase activity. The results demonstrate the effects of controlling dynamically the germination process and improve the understanding of cytolysis in germination.     

High levels of equol in organic skimmed Finnish cow milk

The isoflavonoids, equol, formononetin, daidzein, genistein, biochanin A, and O-demethylangolensin (O-DMA), were analyzed from commercial cartons of skimmed Finnish milk by HPLC-diode array detector (DAD)-FL. We found 411 +/- 65 ng/mL of equol and traces of formononetin and daidzein in organic skimmed milk whereas conventionally produced milk contained 62 +/- 16 ng/mL of equol and no formononetin or daidzein.     

Comparative experimental study of sand and binder for flowability and casting mold quality

A good sand mold is an indispensable prerequisite to obtaining a good metal casting. Although sand casting is one of the oldest metal forming technique known to humans, it still has a lot to discover. In a bid to meet the ever-growing demand for quality, economics and increasing environmental restrictions, research is still ongoing to optimize for example the process of making the sand mold. This paper presents a comparative study of six different foundry sands for flowability using simple inexpensive apparatus and some quality parameters achieved by these sands when used with three different types of binder, two organic and one inorganic. The study aims to facilitate the choice of mold materials with a more extensive outlook into their characteristics through a serious of sand and mold tests. A good comparison of already existing materials provides a good reference point when novel materials are investigated. All the sands exhibited ‘good’ flow property according to the simple flowability tests done. However, not the same consensus for flowability rank is reached by all the flow tests. The mold quality tests reveal the strength, loss on ignition and permeability values achieved with each of the binder and sand combination which can also be used in mold material selection.     

Mechanical and physical properties of thermally modified Scots pine wood in high pressure reactor under saturated steam at 120, 150 and 180 °C

Scots pine sapwood and heartwood were thermally modified under saturated steam at 120, 150 and 180 °C in a high pressure reactor. Mechanical properties such as dynamic and static modulus of elasticity (MOE), static modulus of rupture (MOR), Brinell hardness and impact toughness were evaluated. The static MOE for sapwood did not decrease substantially (approximately 1 %), not even with a high mass loss of more than 12 %, when the wood was modified at 180 °C. Static MOE of the wood increased approximately 14 %, when modified at 150 °C. Surprisingly, MOR increased by 15 %, when modified at 150 °C with mass loss of 2.3 %. Whereas impact strength and hardness decreased somewhat, when modified at 180 °C. Moreover, high anti-swelling efficiency values were obtained (60 % for sapwood and 52 % for heartwood) when modified at 180 °C.     

Cost modelling in underpinning projects

Large refurbishment projects are characterized by highly varied costs from one project to another. In Finnish underpinning, only retrospective analysis of costs has been available for the owner’s decision process. In order to develop tools for pre‐tender cost estimating and for comparison of different design solutions and evaluation of tenders of the underpinning project, two different cost models have been developed for research. In both models developed, the minimum data required is the pile length. In the more detailed model, the assessment is based on the design solution, including known pile types and the load transfer classification. Both models are easy to use, and the percentage of explained variance is fairly good in the more detailed model.