Determination of the critical inclusion size with respect to void formation during hot working

A theory for determining the critical inclusion size with respect to void formation during hot working operation is presented. The theoretical model assumes that the relationship between inclusion size (r) and number (n) is of the typen = 1/r^α. Equations are deduced for the three cases α = 2,α = 3 and α = 4. The most reliable results are obtained if α equals 3 or 4. The critical inclusion size is of the order of 2.5 to 3.5 μm for strains of about 0.7. Formerly with the Department of Ferrous Metallurgy, Royal Institute of Technology, Stockholm.     

A Controlled Experiment Comparing the Maintainability of Programs Designed with and without Design Patterns—A Replication in a Real Programming Environment

Software design patterns seek to package proven solutions to design problems in a form that makes it possible to find, adapt and reuse them. To support the industrial use of design patterns, this research investigates when, and how, using patterns is beneficial, and whether some patterns are more difficult to use than others. This paper describes a replication of an earlier controlled experiment on design patterns in maintenance, with major extensions. Experimental realism was increased by using a real programming environment instead of pen and paper, and paid professionals from multiple major consultancy companies as subjects. Measurements of elapsed time and correctness were analyzed using regression models and an estimation method that took into account the correlations present in the raw data. Together with on-line logging of the subjects work, this made possible a better qualitative understanding of the results. The results indicate quite strongly that some patterns are much easier to understand and use than others. In particular, the Visitor pattern caused much confusion. Conversely, the patterns Observer and, to a certain extent, Decorator were grasped and used intuitively, even by subjects with little or no knowledge of patterns. The implication is that design patterns are not universally good or bad, but must be used in a way that matches the problem and the people. When approaching a program with documented design patterns, even basic training can improve both the speed and quality of maintenance activities.     

Contrast echocardiography for pulmonary blood volume quantification

Pulmonary blood volume quantification is important both for diagnosis and for monitoring of the circulatory system. It requires employment of transpulmonary indicator dilution techniques, which are very invasive due to the need for double catheterization. This paper presents a new minimally invasive technique for blood volume quantification. An ultrasound contrast agent bolus is injected peripherally and detected by an ultrasound transducer in the central circulation. Several echocardiographic views permit simultaneous detection of contrast in different cardiac cavities and central vessels, and acoustic backscatter measurements produce multiple indicator dilution curves (IDCs). Contrast mean-transit-time differences are derived from the IDC analysis and multiplied times cardiac output for the assessment of blood volumes between different detection sites. For pulmonary blood volume estimates, the right ventricle and the left atrium IDCs are measured. The mean transit time of the IDC is estimated by specific modelling. The Local Density Random Walk and the First Passage Time models were tested for IDC interpolation and interpretation. The system was validated in vitro for a wide range of flows. The results show very accurate volume measurements. The volume estimate determination coefficient is greater than 0.999 for both model fits. A preliminary study in patients shows promising results.     

Effects of source shape on the numerical aperture factor with a geometrical-optics model

We study the effects of an extended light source on the calibration of an interference microscope, also referred to as an optical profiler. Theoretical and experimental numerical aperture (NA) factors for circular and linear light sources along with collimated laser illumination demonstrate that the shape of the light source or effective aperture cone is critical for a correct NA factor calculation. In practice, more-accurate results for the NA factor are obtained when a linear approximation to the filament light source shape is used in a geometric model. We show that previously measured and derived NA factors show some discrepancies because a circular rather than linear approximation to the filament source was used in the modeling.     

Motor unit number index (MUNIX)

The surface-recorded compound muscle action potential (CMAP) and electromyographic (EMG) interference pattern is used to compute the motor unit number index (MUNIX). The MUNIX demonstrated all known changes in the number of motor units in normal subjects, and in patients with amyotrophic lateral sclerosis (ALS). In normal subjects MUNIX decreased slightly with age and showed excellent reproducibility. In many ALS patients MUNIX was reduced even when the CMAP was normal. Lower MUNIX values were seen in weaker muscles. This is a noninvasive method that requires minimal electrical stimulation. It is performed in less than 5 min. This makes it suitable for serial EMG investigations.     

How to build a fast and reliable 1024 node cluster with only one disk

In the last year LANL has constructed a 1408-node AMD Opteron cluster, a 1024-node Intel P4 Xeon cluster, a 256-node AMD Opteron cluster and two 128-node Intel P4 Xeon clusters. Each of these clusters is controlled by one front-end node, and each cluster needs only one disk in the front-end node for production operations. In this paper we describe the software architecture that boots and manages these clusters. This software architecture represents a clean break from the way that clusters have been set up for the last 14 years. We show the ways that this architecture has been used to greatly improve the operation of the nodes, with particular emphasis on improvements in boot-time performance, scalability, and reliability. Los Alamos National Laboratory is operated by the University of California for the National Nuclear Security Administration of the United States Department of Energy under contract W-7405-ENG-36. LANL LA-UR-03-9081.     

Wind power in the Danish liberalised power market—Policy measures,price impact and investor incentives

Wind power has a strong position at the Danish electricity market, mainly caused by high feed-in tariffs in the 1990s. Investments in new wind-power installations on land, however, have declined dramatically after the Danish electricity market was liberalised in 1999. First, the paper describes how policy measures directed towards wind power have been redesigned to match the liberalised market. Then, we estimate the impact of the redesigned tariffs on the electricity prices. Finally, we assess whether the new tariffs make an incentive to invest in wind power. The paper concludes that the new tariffs not by itself make evidence for the actual Danish recession in new wind-power installations after the electricity reform. The main causes could include a combination of problems in spatial planning, high risk aversion of new wind turbine investors and perhaps more favourable support schemes in other countries.     

Suicide notes of adolescents: A life-span comparison.

Utilizing suicide notes as the data source, this study begins to explore some psychological dimensions in adolescent suicide and to identify the differences and similarities of suicide across the life span. 80 notes, representing 4 developmental ages (i.e., adolescents, young adults, middle adults, old adults) were analyzed for specific protocols on 8 categories (i.e., unbearable pain, cognitive constriction, indirect expressions, inability to adjust, ego, interpersonal relations, rejection-aggression, and identification-egression). Despite similarities, the results identify that the suicide of teens may be more highly related to cognitive constriction, indirect expressions, rejection-aggression, and identification-egression, than other age groups. Further research beyond the suicides' own narratives (e.g., third-party interviews, study of attempters) is needed to replicate and extend the current findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developing countries and the aircraft industry: match or mismatch?

For many industrially developing countries, technology transfer is seen as a road towards technological and economic development. Indonesian experiences with the aircraft industry suggest that the transfer of technology in this sector is extremely difficult, and even if technology is actually transferred it does not necessarily lead to a viable industry. To determine the key elements for a successful transfer of technology, research was undertaken with a focus on the process of technology transfer at the operational level in industrially developing and developed countries. The research revealed that many technology transfer projects do not or, at best, only marginally contribute to technological development. It also showed that the aircraft industry, and possibly other industries as well, might be better suited to specific countries. To avoid making investments in industries that will inevitably not be competitive, industrially developing countries should be careful when deciding which types of industry to foster.