• Journal of the Korean Mathematical Society
• /
• v.42 no.3
• /
• pp.573-597
• /
• 2005

A continuous linear operator T, on the space of entire functions in d variables, is PDE-preserving for a given set $\mathbb{P}\;\subseteq\;\mathbb{C}|\xi_{1},\ldots,\xi_{d}|$ of polynomials if it maps every kernel-set ker P(D), $P\;{\in}\;\mathbb{P}$, invariantly. It is clear that the set $\mathbb{O}({\mathbb{P}})$ of PDE-preserving operators for $\mathbb{P}$ forms an algebra under composition. We study and link properties and structures on the operator side $\mathbb{O}({\mathbb{P}})$ versus the corresponding family $\mathbb{P}$ of polynomials. For our purposes, we introduce notions such as the PDE-preserving hull and basic sets for a given set $\mathbb{P}$ which, roughly, is the largest, respectively a minimal, collection of polynomials that generate all the PDE-preserving operators for $\mathbb{P}$. We also describe PDE-preserving operators via a kernel theorem. We apply Hilbert's Nullstellensatz.

• International Journal of Quality Innovation
• /
• v.4 no.2
• /
• pp.32-49
• /
• 2003

The interest in on-line services has increased during the last couple of years and there are now several models developed to better understand how customers evaluate e-service quality. In this empirical study we combine the use of the theories of attractive quality and technology readiness so as to explain customer experiences of e-services. A survey was conducted with 188 students at three universities in Sweden, asking how they assess an e-service that enables one to reserve and buy cinema tickets on-line. The main contribution of the study is its provision of evidence on how to interpret and improve customer satisfaction when designing e-services. Our belief is that an organization can gain a clearer grasp of how customer satisfaction is created with an e-service by taking into account customers' experiences with new technology.

• International Journal of Quality Innovation
• /
• v.7 no.1
• /
• pp.48-59
• /
• 2006

The Swedish construction sector has been criticized in media for being corrupted, unproductive and conservative. Several incidents, e.g. cartels, work on the side without paying tax and moisture problems, have had a great deal of attention. Of that reason has the government initiated a number of investigations in order to identify the major problems in the construction industry. Further, they have initiated a development of a tool aimed for (a) to identify risks, (b) to avoid poor quality costs, and (c) to direct towards increased quality and effectiveness in building and civil engineering projects, from a client perspective. The UK Constructing Excellence has often been held up as a model during the debate. However, the Swedish general culture differs from the British, as well as the Swedish system differs from the British. The purpose of this paper is to describe the program for developing the system, including the purposes with the system, identified starting points and demands and the approach/method for the development.

• Journal of Mechanical Science and Technology
• /
• v.20 no.9
• /
• pp.1436-1448
• /
• 2006

This paper describes the effects of injection rate shaping on the combustion, fuel consumption and emission of $NO_x$ and soot of a medium duty diesel engine. The focus is on the influence of four different injection rate shapes, square type 1, square type 2, boot and ramp, with a variation of maximum injection pressure and start of injection (SOI). The experiments were carried out on a 1 liter single cylinder research diesel engine equipped with an amplifier-piston common rail injection system, allowing the adjustment of the injection pressure during the injection event and thus injection rate as desired. Two strategies to maintain the injected fuel mass constant were followed. One where rate shaping is applied at constant injection duration with different peak injection pressure and one strategy where rate shaping is applied at a constant peak injection pressure, but with variable injection duration. Injection rate shaping was found to have a large effect on the premixed and diffusion combustion, a significant influence on $NO_x$ emissions and depending on the followed strategy, moderate or no influence on soot emission. Only small effects on indicated fuel consumption were found.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10a
• /
• pp.259-262
• /
• 1996

This paper proposes an approach in modeling a 4x60inch Allis Chalmers Hydrocone Crusher [1] hydroset and presents some numerical simulation results. The mining and quarry industry is one of the industries which extensively use hydrocone crushers, which are a family of cone crushers, for rock size reduction. Field studies have proved that if proper control and management of these machines is undertaken, they can yield an increased production output of more than 30%, in addition substantial savings in both energy consumption per unit ton produced and manpower can be easily realized. In order to achieve these economic benefits, high performance from these machines is expected. Implementing automatic control for such machines would be a great leap towards achieving both economic benefits and more effective fool-proof predictive maintenance. But, unfortunately, for such a control system to be designed, it necessary to make a mechatronical model of this plant. The plant model is able to give us an insight into variations of both the plant gap setting (displacement) and system pressure due to variable loading arising from the crushing process.

• Steel and Composite Structures
• /
• v.2 no.5
• /
• pp.379-396
• /
• 2002

The paper describes the mechanical behavior of short concrete-filled steel tube (CFT) columns with circular section. The efficiency of the steel tube in confining the concrete core depending on concrete strength and the steel tube thickness was examined. Fifteen columns were tested to failure under concentric axial loading. Furthermore, a mechanical model based on the interaction between the concrete core and the steel tube was developed. The model employs a volumetric strain history for the concrete, characterized by the level of applied confining stress. The situation of passive confinement is accounted for by an incremental procedure, which continuously updates the confining stress. The post-yield behavior of the columns is greatly influenced by the confinement level and is related to the efficiency of the steel tube in confining the concrete core. It is possible to classify the post-yield behavior into three categories: strain softening, perfectly plastic and strain hardening behavior. The softening behavior, which is due to a shear plane failure in the concrete core, was found for some of the CFT columns with high-strength concrete. Nevertheless, with a CFT column, it is possible to use high-strength concrete to obtain higher load resistance and still achieve a good ductile behavior.

• Proceedings of the KSME Conference
• /
• 2001.11b
• /
• pp.423-425
• /
• 2001

The Proper Orthogonal Decomposition (POD) technique was applied to investigate the effects of Reynolds number and the characteristics of the organized motions or coherent structures as a function of downstream position from x/D=2 to 6 in a turbulent axisymmetric shear layer at Reynolds numbers of 78,400, 117,600, and 156,800. Data were collected simultaneously using the 138 hot-wire probe used by Citriniti and George (2000). The POD was then applied to a double Fourier transform in time and azimuthal direction of the double velocity correlation tensor. The lowest azimuthal mode for all POD modes, which dominated the dynamics at x=D = 3 in the previous experiments, dies off rapidly downstream. This is consistent with a trend toward homogeneity in the downstream evolution, and suggests that some residual value may control the growth rate of the far jet. On the other hand, for the higher azimuthal modes, the peak shifts to lower mode numbers and actually increases with downstream distance. These mixing layer data, normalized by similarity variables for the mixing layer, collapse at all downstream positions and are nearly independent of Reynolds numbers.

• Steel and Composite Structures
• /
• v.3 no.1
• /
• pp.47-64
• /
• 2003

In a nonlinear finite element study on the mechanical behavior of simple beam connections to continuous concrete-filled steel tube columns, two principally different connection types were analyzed: one with plates attached to the outside of the tube wall, relying on shear transfer, and one with an extended plate inserted through the steel section to ensure bearing on the concrete core. The load was applied partly at the connection within the column length and partly at the top, representing the load from upper stories of a multistory building. The primary focus was on the increased demand for load transfer to ensure composite action when concrete with higher compressive strength is used. The results obtained from the analyses showed that the design bond strength derived from push tests is very conservative, mainly due to the high frictional shear resistance offered by pinching and contraction effects caused by connection rotation. However, with higher concrete strength the demand for load transfer increases, and is hard to fulfill for higher loads when connections are attached only to the steel section. Instead, the connection should penetrate into the concrete core to distribute load to the concrete by direct bearing.

• Nuclear Engineering and Technology
• /
• v.49 no.6
• /
• pp.1301-1309
• /
• 2017

The extinction probability of a branching process (a neutron chain in a multiplying medium) is calculated for a system randomly varying in time. The evolution of the first two moments of such a process was calculated previously by the authors in a system randomly shifting between two states of different multiplication properties. The same model is used here for the investigation of the extinction probability. It is seen that the determination of the extinction probability is significantly more complicated than that of the moments, and it can only be achieved by pure numerical methods. The numerical results indicate that for systems fluctuating between two subcritical or two supercritical states, the extinction probability behaves as expected, but for systems fluctuating between a supercritical and a subcritical state, there is a crucial and unexpected deviation from the predicted behaviour. The results bear some significance not only for neutron chains in a multiplying medium, but also for the evolution of biological populations in a time-varying environment.

• International Journal of Quality Innovation
• /
• v.7 no.1
• /
• pp.20-34
• /
• 2006

The purpose of this study is to investigate what happens within an organization when a process view of the business is adopted. With the example of an empirical case, we aim to illustrate: how members of the organization make sense of process management; what contributions members of the organization consider to be the result of adopting a process view; and the relationship between the functional and the process structure. The empirical base in this study is one of Sweden's largest purchasing organizations within the public sector. The results are drawn from interviews with the process owners and a survey to all members involved in process teams. The case findings reveal an ambiguous image of process management. At the same time as process management solved specific organizational problems, it generated new dilemmas. It is argued that it is more rewarding to consider the adoption of the process view a 'social negotiation' rather than the result of planned implementation. The study also highlights that the meaning of process management is not anything given but something being created, and its negotiation and translation into organizational practice is open-ended. Furthermore, the study gives an illustration of the conflict between the adopted process view and the existing functional organization.