Dynamic control of the permanent magnet-assisted reluctance synchronous machine

A digital signal processor-based control system for the permanent magnet-assisted reluctance synchronous machine, with the emphasis on dynamic performance, is proposed. A classical design approach is used to design the current and speed controllers for the machine. The stator current of the machine is controlled in such a way that the current angle in the dq synchronous reference frame is constant. The load-torque is estimated using a state space observer and compensation current based on the estimated load is used to improve the dynamic performance of the drive. The control system design is machine specific as it relies on data from finite-element analysis. Simulated and measured results on a 110-kW power level show that the resulting control system is stable and robust with good dynamic performance     

An empirical investigation on how portfolio risk management influences project portfolio success

Project risk management is recognized as essential in order to cope with the challenges arising from the environment. Literature suggests a portfolio-wide perspective for managing risks in project portfolios. However, research on risk management and its success in a project portfolio context is scarce. This study examines how portfolio risk management influences project portfolio success. Using a sample of 176 firms, this study provides evidence that portfolio risk identification, the formalization of the portfolio risk management process, and risk management culture directly influence risk transparency, whereas risk prevention, risk monitoring, and the integration of risk management into project portfolio management are directly connected to risk coping capacity. The findings also suggest that both risk transparency and risk coping capacity have a direct impact on project portfolio success. However, the results did not confirm the hypothesis that risk transparency and risk coping capacity have a complementary effect on success. Implications for scholars and project portfolio managers are discussed.     

Behavior of internal stakeholders in project portfolio management and its impact on success

Stakeholder behavior and stakeholder management are key success factors within project portfolio management (PPM). This empirical study of 197 project portfolios investigates the effect of the intensity of engagement (IoE) of portfolio-internal stakeholders on project portfolio success. We show that the effect of stakeholders is phase-specific and that role clarity as a measure of PPM maturity affects the nature of the relationship between the IoE of stakeholders and portfolio success. The effects of the IoE of senior managers on success are not clearly positive with regard to strategic portfolio structuring and are even negative in operative portfolio steering in established PPM systems. In immature PPM systems, line managers tend to take advantage of their position in resource management. Surprisingly, the influence of portfolio managers in portfolio steering is insignificant. Altogether, this paper shows the diverse effect of the IoE of stakeholders on portfolio success. This study enriches project research by applying stakeholder theory to the project portfolio context and offers practical guidance for further professionalizing PPM.     

Antarctic springtime depletion of atmospheric mercury

Unlike other heavy metals that are inherently associated with atmospheric aerosols, mercury in ambient air exists predominantly in the gaseous elemental form. Because of its prolonged atmospheric residence time, elemental mercury vapor is distributed on a global scale. Recently, Canadian researchers have discovered that total gaseous mercury levels in the lower tropospheric boundary layer in the Canadian Arctic are often significantly depleted during the months after polar sunrise. A possible explanation may involve oxidation of elemental mercury, followed by adsorption and deposition of the oxidized form, leading to an increased input of atmospheric mercury into the Arctic ecosystem. Here we present the first continuous high-time-resolution measurements of total gaseous mercury in the Antarctic covering a 12-month period between January 2000 and January 2001 at the German Antarctic research station Neumayer (70 degrees 39' S, 8 degrees 15' W). We report that mercury depletion events also occur in the Antarctic after polar sunrise and compare our measurements with a data setfrom Alert, Nunavut, Canada. We also present indications that BrO radicals and ozone play a key role in the boundary-layer chemistry during springtime mercury depletion events in the Antarctic troposphere.     

Low molecular weight oligo-β-hydroxybutyric acids and 3-hydroxy-N-phenethyl-butyramide – new products from microorganisms

Summary A new group of low-molecular weight channel-forming oligo(hydroxybutyric acids) (cPHBs, 1 with n = 8–30; main component MW ≈ 1300 dalton) was isolated from microorganisms of different origin. Inclusion bodies were electron-microscopically visible in cells in the state of autolysis, not in cells in the exponential phase of growth. cPHB and high-molecular poly(l3-hydroxybutyric acid) (sPHB) is cleaved by phenylethylamine and forms the corresponding monomeric hydroxybutyramide and – under drastic conditions, the crotylamide. One of these compounds, the 3-hydroxy-N-phenethyl-butyramide (5), was isolated as a new natural product now. Received: 28 March 2002/Revised version: 26 July 2002/ Accepted: 26 July 2002 RID="*" ID="*"Marine Bakterien, XVII. XVI: R.P. Maskey, R.N. Asolkar, E. Helmke, and H. Laatsch, Chalcomycin B, a new antibiotic from a marine Streptomyces sp. B7064. J. Antibiot., submitted 2002 Correspondence to Hartmut Laatsch, e-mail: hlaatsc@gwdg.de, Fax: +49-551-399660     

Oilseed pretreatment in connection with physical refining

Tests have shown that the nonhydratable phosphatides (NHP) arising by the action of phospholipases are not present in significant quantities in commercial soybeans, but that they are formed predominantly only during extraction. By a moisture-heat treatment of the soy flakes prior to the extraction, this enzyme activity can be almost completely eliminated so that, during the subsequent extraction, an enzymatic change of the oil no longer occurs. In comparison with the extraction of untreated soy flakes, the yield of soy lecithin is doubled; the lecithin has a higher content of phosphatidylchol ine; the crude, degummed soy oil has extraordinarily low NHP contents; and the soy meal tastes less bitter.     

A Clustering Approach to Explore Grain-Sizes in the Definition of Processing Elements in Dataflow Architectures

We explore the area efficiency of a class of stream-based dataflow architectures as a function of the grain-size, for a given set of applications. We believe the grain-size is a key parameter in balancing flexibility and efficiency of this class of architectures. We apply a clustering approach on a well-defined set of applications to derive a set of processing elements of varying grain-sizes. The resulting architectures are compared with respect to their silicon area. For a set of twenty-one industrially relevant video algorithms, we determined architectures with various grain-sizes. The results of this exercise indicate an improvement factor of two for the silicon area, while changing the grain-size from fine-grain to coarser-grain.     

Asynchronous and distributed process improvement: the role of collaborative technologies

Abstract. The recent proliferation of low-cost computer networks has driven the development of a new type of organization, in which geographical and time constraints to collaboration among process teams have been gradually removed. As these organizations have to cope with a fast pace of change, they rely increasingly on distributed and asynchronous process improvement (PI) groups to redesign their processes. Yet little is known about the effects of asynchronous group support systems (GSSs) on PI groups. We investigate the effects of asynchronous GSSs on PI groups through a two-stage action research study of 38 such groups in three organizations, one in Brazil and two in New Zealand, over 4 years and 4 months. Different PI groups voluntarily conducted all, part or none of their communication through an e-mail conferencing (EC) tool. The research suggests that EC support causes a decrease in the organizational costs associated with PI groups, which, combined with an increase in the number of possible simultaneous PI groups, generates an increase in overall organizational PI efficiency. The research also suggests a neutral overall effect of EC support on PI group outcome quality. Two explanatory causal models summarizing these effects are developed, and implications for research and industry practice are discussed.