The convergence of functions to fixedpoints of recursive definitions

The classical method for constructing the least fixedpoint of a recursive definition is to generate a sequence of functions whose initial element is the totally undefined function and which converges to the desired least fixedpoint. This method, due to Kleene, cannot be generalized to allow the construction of other fixedpoints. In this paper we present an alternate definition of convergence and a new fixedpoint access method of generating sequences of functions for a given recursive definition. The initial function of the sequence can be an arbitrary function, and the sequence will always converge to a fixedpoint that is “close” to the initial function. This defines a monotonic mapping from the set of partial functions onto the set of all fixedpoints of the given recursive definition.     

Mitigation of carbon dioxide from Indonesia's energy system

In Indonesia, energy consumption (excluding non-commercial energy) increased from 328 MBOE in 1990 to 478 MBOE in 1995. As a consequence, energy sector CO₂ emissions increased from 150 million tons to over 200 million tons during the same period. The present rapid economic growth Indonesia is experiencing (7–8%) will continue in the future. Based on a BAU scenario, primary energy supply for the year 2020 will be 18,551 PJ, an increase of 5.9% annually from 1990 CO₂ from the energy system will increase from 150 Teragrams in 1990 to 1264 Teragram in 2020. The mitigation scenario would reduce total CO₂ emissions from the BAU scenario by 10% for the year 2000 and 20% by 2020. Some demand side management and energy conservation programs are already included in the BAU scenario. In the mitigation scenario, these programs are expanded, leading to lower final energy demand in the industrial and residential sectors.

Indonesia's total primary energy supply in 2020 is approximately 5% lower for the mitigation scenario than for the BAU scenario. In the BAU scenario, coal and oil have the same contribution (25%). In the mitigation scenario, natural gas and nonfossil fuels such as hydropower, geothermal, and nuclear have higher contributions.     

New Analysis of the Du Fort–Frankel Methods

In 1953 Du Fort and Frankel (Math. Tables Other Aids Comput., 7(43):135?C152, 1953) proposed to solve the heat equation u _t =u _xx using an explicit scheme, which they claim to be unconditionally stable, with a truncation error is of order of $\tau= O({{k}}^{2}+{{h}}^{2}+\frac{{{k}}^{2}}{{{h}}^{2}})$ . Therefore, it is not consistent when k=O(h). In the analysis presented below we show that the Du Fort?CFrankel schemes are not unconditionally stable. However, when properly defined, the truncation error vanishes as h,k??0.     

Information Filtering: A New Two-Phase Model Using Stereotypic User Profiling

Computer users often experience the lost in informationspace syndrome. Information filtering suggests a solution based onrestricting the amount of information made available to users. Thisstudy suggests an advanced model for information filtering which isbased on a two-phase filtering process. The user profiling in themodel is constructed on the basis of the user's areas of interestand on sociological parameters about him that are known to thesystem. The system maintains a database of known stereotypes thatincludes rules on their information retrieval needs and habits.During the filtering process, the system relates the user to one ormore stereotypes and operates the appropriate stereotypic rules.     

Single image face orientation and gaze detection

We introduce a system to compute both head orientation and gaze detection from a single image. The system uses a camera with fixed parameters and requires no user calibration. Our approach to head orientation is based on a geometrical model of the human face, and is derived form morphological and physiological data. Eye gaze detection is based on a geometrical model of the human eye. Two new algorithms are introduced that require either two or three feature points to be extracted from each image. Our algorithms are robust and run in real-time on a typical PC, which makes our system useful for a large variety of needs, from driver attention monitoring to machine-human interaction.     

Improved Related-key Attacks on DESX and DESX+

Abstract

In this article, we present improved related-key attacks on the original DESX, and DESX+, a variant of the DESX with its pre- and post-whitening XOR operations replaced with addition modulo 2⁶⁴. Compared to previous results, our attack on DESX has reduced text complexity, while our best attack on DESX+ eliminates the memory requirements at the same processing complexity.     

Spontaneous core-sheath formation in electrospun nanofibers

In recent research, electrospun nanofibers (NFs) from polymer solutions containing metal salts were used to produce high-temperature superconducting ceramic (HTSC) NFs through pyrolysis. In this research, the production of phase separated nanostructures inside NFs spun from polymer solutions containing metal salts was investigated. The metal salts were expected to be preferentially driven into one of the phases (the amorphous phase in a semi-crystalline polymer and the more hydrophilic phase in a triblock copolymer) and yield nanostructured ceramics upon pyrolysis. Surprisingly, the electrospun NFs exhibited the spontaneous formation of a core-sheath structure. The metal-atom-rich core exhibited a 10 nm scale structure while no such structure was observed in the metal-atom-poor sheath. Both the repulsion of metal atoms by the positive surface charge and the exclusion of the metal atoms from the crystallizing front that moves inward from the surface were shown to contribute to the spontaneous formation of the core-sheath structure.