Efficient filtering for the Resource-Cost AllDifferent constraint

This paper studies a family of optimization problems where a set of items, each requiring a possibly different amount of resource, must be assigned to different slots for which the price of the resource can vary. The objective is then to assign items such that the overall resource cost is minimized. Such problems arise commonly in domains such as production scheduling in the presence of fluctuating renewable energy costs or variants of the Travelling Salesman Problem. In Constraint Programming, this can be naturally modeled in two ways: (a) with a sum of element constraints; (b) with a MinimumAssignment constraint. Unfortunately the sum of element constraints obtains a weak filtering and the MinimumAssignment constraint does not scale well on large instances. This work proposes a third approach by introducing the ResourceCostAllDifferent constraint and an associated incremental and scalable filtering algorithm, running in \(\mathcal {O}(n \cdot m)\), where n is the number of unbound variables and m is the maximum domain size of unbound variables. Its goal is to compute the total cost in a scalable manner by dealing with the fact that all assignments must be different. We first evaluate the efficiency of the new filtering on a real industrial problem and then on the Product Matrix Travelling Salesman Problem, a special case of the Asymmetric Travelling Salesman Problem. The study shows experimentally that our approach generally outperforms the decomposition and the MinimumAssignment ones for the problems we considered.     

Evaluation of six night vision enhancement systems: qualitative and quantitative support for intelligent image processing

OBJECTIVE: An evaluation study was conducted to answer the question of which system properties of night vision enhancement systems (NVESs) provide a benefit for drivers without increasing their workload. BACKGROUND: Different infrared sensor, image processing, and display technologies can be integrated into an NVES to support nighttime driving. Because each of these components has its specific strengths and weaknesses, careful testing is required to determine their best combination. METHOD: Six prototypical systems were assessed in two steps. First, a heuristic evaluation with experts from ergonomics, perception, and traffic psychology was conducted. It produced a broad overview of possible effects of system properties on driving. Based on these results, an experimental field study with 15 experienced drivers was performed. Criteria used to evaluate the development potential of the six prototypes were the usability dimensions of effectiveness, efficiency, and user satisfaction (International Organization for Standardization, 1998). RESULTS: Results showed that the intelligibility of information, the easiness with which obstacles could be located in the environment, and the position of the display presenting the output of the system were of crucial importance for the usability of the NVES and its acceptance. Conclusion: All relevant requirements are met best by NVESs that are positioned at an unobtrusive location and are equipped with functions for the automatic identification of objects and for event-based warnings. APPLICATION: These design recommendations and the presented approach to evaluate the systems can be directly incorporated into the development process of future NVESs.     

Identification of statistical patterns in complex systems via symbolic time series analysis

Identification of statistical patterns from observed time series of spatially distributed sensor data is critical for performance monitoring and decision making in human-engineered complex systems, such as electric power generation, petrochemical, and networked transportation. This paper presents an information-theoretic approach to identification of statistical patterns in such systems, where the main objective is to enhance structural integrity and operation reliability. The core concept of pattern identification is built upon the principles of Symbolic Dynamics, Automata Theory, and Information Theory. To this end, a symbolic time series analysis method has been formulated and experimentally validated on a special-purpose test apparatus that is designed for data acquisition and real-time analysis of fatigue damage in polycrystalline alloys.     

High-level user interfaces for transfer function design with semantics

Many sophisticated techniques for the visualization of volumetric data such as medical data have been published. While existing techniques are mature from a technical point of view, managing the complexity of visual parameters is still difficult for non-expert users. To this end, this paper presents new ideas to facilitate the specification of optical properties for direct volume rendering. We introduce an additional level of abstraction for parametric models of transfer functions. The proposed framework allows visualization experts to design high-level transfer function models which can intuitively be used by non-expert users. The results are user interfaces which provide semantic information for specialized visualization problems. The proposed method is based on principal component analysis as well as on concepts borrowed from computer animation.     

Relational mountain (density) clustering method and web log analysis

The mountain clustering method and the subtractive clustering method are useful methods for finding cluster centers based on local density in object data. These methods have been extended to shell clustering. In this article, we propose a relational mountain clustering method (RMCM), which produces a set of (proto) typical objects as well as a crisp partition of the objects generating the relation, using a new concept that we call relational density. We exemplify RMCM by clustering several relational data sets that come from object data. Finally, RMCM is applied to web log analysis, where it produces useful user profiles from web log data. © 2005 Wiley Periodicals, Inc. Int J Int Syst 20: 375–392, 2005.     

Snakes on the watershed

We present a new approach for object boundary extraction, called the watersnake. It is a two-step snake algorithm whose energy functional is minimized by the dynamic programming method. It is more robust to local minima because it finds the solution by searching the entire energy space. To reduce the complexity of the minimization process, the watershed transformation and a coarse-to-fine strategy are used. The new technique is compared to standard methods for accuracy in synthetic data and is applied to segmentation of white blood cells in bone marrow images     

The supercooling dependence of the initial fold length of polyethylene crystallized from the melt: unification of melt and solution crystallization

Following the previous recognition [1], reached with the aid of real time low angle X-ray diffraction (using a synchrotron X-ray source) that in melt crystallized polyethylene the initial (primary) lamellar thickness is much smaller than hitherto envisaged, we have proceeded to construct the full relationship between primary fold length (I _g ^*) and supercooling (T) covering a wide range of crystallization temperature (T _c). The principal result of this work is the identification of supercooling as the sole factor which determinesI _g ^*. Comparison with crystallization from solution [2–4] has revealed that theI _g ^* against T curves are completely superposable thus removing the gap which has existed up to the present between melt and solution crystallization, bringing about a welcome unification of these two separate (at least as far as fold length was concerned) aspects of polymer crystallization. Further, we show that while T determinesI _g ^*, subsequent thickening is determined by the absolute temperature. Isothermal thickening in particular proceeds first by a large discontinuous step followed by a continuous logarithmic increase with time. The importance of these findings and in particular the affirmation of the unique role of supercooling for chain folding and lamellar crystallization in general is emphasized.     

High-temperature crystallization behaviour of amorphous Fe80B20

Samples of 0.003 in. round Fe₈₀B₂₀ amorphous wires were annealed in vacuo for 1 sec to 8 h periods at 780° C and the crystallinity induced in these wires from this heat treatment was studied through X-ray diffraction and field-ion microscopy. X-ray diffraction studies indicate that complete crystallinity is produced following 1 sec anneal at 780° C. However, the initial product is a primitive-tetragonal Fe₃B phase unlike the body-centred tetragonal Fe₃B observed in low-temperature isothermal transformation studies with this alloy. The Fe₃B phase is seen to persist in the diffraction patterns for annealing durations of up to 15 min. Upon annealing for periods of up to 1 h, an intermediate three-phase structure consisting of -Fe, Fe₃B, and Fe₂B is seen to result with a gradual decrease in the Fe₃B phase corresponding to longer annealing durations. Anneals of more than 1 h at 780° C are seen to result in the disappearance of the Fe₃B phase producing a two-phase microstructure consisting of -Fe(b c c) and Fe₂B (b c t). Field-ion-microscopy with a pure neon imaging gas at 78 K likewise indicates that existence of a three-stage phase structural change during the isothermal anneals, and the atomic arrangement of the various species are quite readily discernible because of the different symmetries contained in the three distinct phases.     

Annealing behaviour of amorphous Fe80B20 on continuous heating

Resistance measurements during direct heating of Fe₈₀B₂₀ amorphous alloys indicate phase changes occur at 395, 500, 720 and 840° C. Samples heated to these temperatures, and maintained for five minutes in a neutral atmosphere, show that a hardness maximum occurs at the crystallization temperature of 395° C and that annealing at 500° C produces a material with the same hardness. Above 500° C the microhardness is seen to drop below that of the amorphous alloy. Saturation magnetization measurements show a steady increase following each anneal, up to a temperature of 720° C, and the rate of increase is seen to drop in the range of 720 to 840° C. X-ray diffraction studies show that only a small fraction of the matrix is crystallized following the anneal at 395° C and the transformed phases are -Fe and Fe₃B. Following annealing at 500° C, an increased proportion of -Fe and Fe₃B are observed with complete crystallinity while samples heattreated at 720° C are seen to consist of a three-phase mixture of -Fe, Fe₂₃B₆ and Fe₂B. Annealing at 840° C is seen to produce an equilibrium phase mixture of -Fe and Fe₂B phases. Only in the sample annealed at 395° C is a fraction of the amorphous phase seen to persist, indicating that a 5 min anneal is not sufficient, at this temperature, to induce complete crystallization. These structural features are corroborated by field ion microscope analyses, made at liquid nitrogen temperature in a medium of pure neon, and scanning electron microscopy, and are also consistent with our earlier study involving the isothermal annealing, for various times, of Fe₈₀B₂₀ alloy at 780° C.     

AH-64D main transmission accessory drive spur gear installation fault detections

The US Army has launched an aggressive program to implement condition based maintenance on its rotary wing assets. Condition Based Maintenance takes advantage of technology developments in the areas of machinery monitoring, signal processing and fault modeling to reduce the cost of ownership through improved maintenance procedures. Documenting the reduction in maintenance burden, cost savings and increased safety through early detection of helicopter faults is an important step in justifying the program. This paper describes a novel technique used to detect a serious fault in the accessory section of the AH-64D Apache main transmission. The technique determines if the primary or secondary clutch system is driving the aircraft accessories through a tachometer speed ratio. The method has identified three aircraft operating on the secondary system allowing Army maintenance crews to replace the affected transmissions and quickly restore the aircraft to operational status.