Effect of pressure and impurities on oxidation in supercritical CO2

Both indirect‐ and direct‐fired supercritical CO₂ cycles for high‐efficiency power generation are expected to have impurities that may greatly alter the compatibility of Fe‐ and Ni‐based structural alloys in these environments. Recent work has attempted to quantify reaction rates at 750°C in simulated laboratory environments with controlled impurity levels at ambient pressure, as well as under supercritical conditions (30 MPa). With low impurity levels in research and industrial‐grade CO ₂, pressure appeared to have only a limited effect on oxide thickness and internal oxidation and reaction products were similar to those formed in laboratory air. However, a direct‐fired simulation at 750°C/30 MPa in CO ₂ + 1%O ₂ + 0.25%H ₂O has found an increased mass gain and characterization after 2,500‐hr exposures have found thicker reaction products, especially for Fe‐based alloys. At these impurity levels, pressure may have a significant effect on the role of impurities.     

Gameful Experience Questionnaire (GAMEFULQUEST): an instrument for measuring the perceived gamefulness of system use

User Modeling and User-Adapted Interaction - In this paper, we present the development and validation of an instrument for measuring users’ gameful experience while using a service. Either...     

Parental worry about indoor air quality and student symptom reporting in primary schools with or without indoor air quality problems

Poor indoor air quality (IAQ) in schools is related to increased symptom reporting in students. We investigated whether parental worry about school IAQ influences this association. Data came from survey collected from five Finnish primary schools with observed IAQ problems and five control schools. Parents (n = 1868) of primary school students reported worry about IAQ in schools and symptoms of their children. Associations between observed IAQ problems, worry, and five symptom scores (ie, respiratory, lower respiratory, eye, skin, and general symptoms) were analyzed using multivariate logistic regression and mediation analysis. Parents were on average more worried in schools with observed IAQ problems. Observed IAQ problems were strongly associated with increased worry and all symptoms under study (unadjusted ORs ranged between 1.48 [95% CI 1.48‐2.16] and 2.70 [95% CI 1.52‐5.17]). Parental worry was associated with all symptoms (unadjusted ORs ranged between 2.49 [95% CI 1.75‐3.60] and 4.92 [95% CI 2.77‐9.40]). Mediation analyses suggested that parental worry might partially explain the association between observed IAQ problems and symptom reporting (proportion mediated ranged between 67% and 84% for the different symptoms). However, prospective studies are needed to assess causal relationships between observed IAQ problems, worry, and symptom reporting in schools.     

Fuzzy feed rate and cutting speed optimization in turning

There are several methods of monitoring metal cutting processes. In this study, the combination of various methods in order to define an overall “cutting state” of a turning process is discussed along with an application to use these methods for adaptive fuzzy feed rate and cutting speed optimising control. For this purpose, different methods of monitoring individual cutting phenomena such as chip length and vibration level are aggregated and the combination of this information is considered to be the cutting state of the process. Expert data has been collected from a series of experiments concerning the apparent state of these phenomena as well as required control action. An adaptive optimizing fuzzy controller has been designed based on the concept of the cutting state and collected expert rules. The automatically classified cutting state as well as the control action based on this state is compared to expert data. There are notable differences which are analysed and solutions and further research are suggested based on the points requiring further improvement.     

Regeneration and Recycling of Aqueous Periodate Solution in Dialdehyde Cellulose Production

Abstract

The regeneration of aqueous iodate solution from the regioselective periodate oxidation of softwood cellulose pulp to dialdehyde cellulose using hypochlorite as a secondary oxidant was studied. The influence of oxidation time on the pulp dissolution and regeneration efficacy was examined in particular. In addition, the recycling of regenerated periodate solution back to oxidation was clarified. The solutions from the 10 and 15 min oxidations were regenerated with 100% conversion efficacy when 1.2–1.4 times the stoichiometric amounts of hypochlorite were used. However, the regeneration efficacy decreased when the reaction time in the oxidation increased to 30 min because the content of soluble impurities, which consumed the hypochlorite in the side-reactions, increased significantly as the oxidation reaction proceeded. The regenerated solutions possessed good oxidation performance, showing that periodate was successfully regenerated using hypochlorite and supporting the assumption that periodate can be effectively recycled in the process when short oxidation times are used.     

The effect of the stabilization period on the economic lot scheduling problem

The Economic Lot Scheduling Problem (ELSP) is the problem of scheduling production of several items in a single facility, so that demands are met without stockouts or backorders, and the long run average inventory carrying and setup costs are minimized. One of the general assumptions in the ELSP is that the yield rates of a given manufacturing process are constant, or 100%, after setup. However, this assumption may not be true for certain manufacturing processes, in which the yield rates are quite low just after setup, and then increase over time. This period is called a stabilization period and yield rates gradually increase during this period until they reach the target rates, which are set empirically or strategically. The purpose of this paper is to clarify the effect of the stabilization period by applying the stabilization period concept to the ELSP, which has been widely applied to many production systems. In this paper, the problem is tackled in three stages: Firstly, we formulate a model and develop an algorithm, which provides a lower bound for a minimum cost. Secondly, we develop a heuristic procedure using the time-varying lot size approach. Finally, we solve a special case of the ELSP to find an upper bound using the common cycle approach.     

A systematic approach to business process reengineering

In this study, a business process is defined as a set of various tasks which are closely inter-related and is assumed to have its own objectives to achieve. A set of processes constitute a business system. Many business process reengineering plans turned out to be unsuccessful because they are based on the existing process which assumed tasks along the process independent or based on the assumption that a process is independent of other processes. This approach generated redundant tasks or led to conflict between business processes. Under this approach, it very difficult to predict the result of the plan due to localized analysis of the process. To avoid aforementioned problems, a systematic, analytic and iterative approach to build up a master plan for business process reengineering is proposed.     

Necessary and Sufficient Pre-processing in Numerical Range Discretization

The time complexities of class-driven numerical range discretization algorithms depend on the number of cut point candidates. Previous analysis has shown that only a subset of all cut points - the segment borders - have to be taken into account in optimal discretization with respect to many goodness criteria. In this paper we show that inspecting segment borders alone suffices in optimizing any convex evaluation function. For strictly convex evaluation functions inspecting all of them also is necessary, since the placement of neighboring cut points affects the optimality of a segment border. With the training set error function, which is not strictly convex, it suffices to inspect an even smaller set of cut point candidates, called alternations, when striving for optimal partition. On the other hand, we prove that failing to check an alternation may lead to suboptimal discretization. We present a linear-time algorithm for finding all alternation points. The number of alternation points is typically much lower than the total number of cut points. In our experiments running the discretization algorithm over the sequence of alternation points led to a significant speed-up.     

Neural Network-Based Artificial Bandwidth Expansion of Speech

The limited bandwidth of 0.3-3.4 kHz in current telephone systems reduces both the quality and the intelligibility of speech. Artificial bandwidth expansion is a method that expands the bandwidth of the narrowband speech signal in the receiving end of the transmission link by adding new frequency components to the higher frequencies, i.e., up to 8 kHz. In this paper, a new method for artificial bandwidth expansion, termed Neuroevolution Artificial Bandwidth Expansion (NEABE) is proposed. The method uses spectral folding to create the initial spectral components above the telephone band. The spectral envelope is then shaped in the frequency domain, based on a set of parameters given by a neural network. Subjective listening tests were used to evaluate the performance of the proposed algorithm, and the results showed that NEABE speech was preferred over narrowband speech in about 80% of the test cases