Stacked multijunction photodetectors of long-wavelength radiation

Uncooled, long-wavelength photovoltaic detectors suffer from poor quantum efficiency and low differential resistance. The problem can be solved by the use of stacked, multiple heterojunction-photovoltaic cells with thin absorber regions. We report here numerical simulation and optimization of the stacked, multiple Hg_1−xCd_xTe heterojunction cells used for detection of 10.6-μm infrared (IR) radiation, operating as zero-bias photovoltaic devices or Auger-suppressed photodiodes. It is shown that the devices can be used as high-performance and fast-response detectors of long-wavelength radiation operating at ambient temperature with detectivities larger by more than one order of magnitude than that of the present practical devices.     

Knowledge verification for fuzzy expert systems

Abstract

The introduction and use of fuzzy logic has strengthened knowledge representation and reasoning capability in expert systems; nevertheless, it also increases the complexity and difficulty of knowledge verification, which is known to be an important issue for building reliable and high performance expert systems. In the past decade, knowledge verification problems, e.g., redundancy, conflict, circularity and incompleteness of knowledge, have been widely discussed from the viewpoint of using binary logic; nevertheless, the issue of verifying fuzzy knowledge is seldom discussed. In this paper, we attempt to detect potential structural errors among fuzzy rules by proposing a fuzzy verification algorithm. Moreover, a system for verifying fuzzy knowledge base has been developed based on the novel approach.     

Corrected 2D-theories for composite plates

Summary The objective of the paper is to propose a simple method of formulation of 2D-theories for composite thin plates made of an arbitrary inhomogeneous linear-elastic material. The effect of inhomogeneity on the plate stiffness will be described by means of extra unknowns, called correctors, which have to satisfy a system of linear algebraic equations. The elimination of correctors can be performed in explicit form and leads to the formulas for effective stiffnesses of the plates under consideration.     

Creep crack growth in fiber reinforced composites with rate-dependent bridging - Role of a viscous fiber matrix interface

A model is developed for creep crack growth in continuous fiber reinforced composites wherein a growing matrix crack is subjected to rate-dependent bridging by unbroken fibers. The rate-dependence in this model arises as a result of the presence of a viscous fiber/matrix interfacial layer. Under load this layer undergoes shear flow causing time-dependent pull-out of bridging fibers from the crack surfaces. The mechanics of time-dependent bridging is combined with a failure criterion based on secondary failure in a crack-tip creep process zone. The dependence of the matrix creep crack growth rates on flaw size and crack wake parameters as well as on composite microstructure is derived. It is shown that the crack wake plays a predominant role in influencing not only the magnitude of creep crack growth rates but also the relationship of growth rates to the crack sizes. A closed form expression is derived for the dependence of crack growth rates on loading, creep and bridging parameters in the regime wherein crack growth rates are independent of crack size.     

One Method of Determination of the Effective Absorption Coefficient in Pulsed Laser Irradiation of Metals

An experimentaltheoretical method of determination of the absorption coefficients in laser treatment of metals has been proposed based on the solution of the boundaryvalue axisymmetric problem of heat conduction for a halfspace and metallographic measurements of the dimensions of the thermalhardening zone.     

Electronic and Excitonic Properties of MSi2Z4 Monolayers

MA₂Z₄ monolayers form a new class of hexagonal non-centrosymmetric materials hosting extraordinary spin-valley physics. While only two compounds (MoSi₂N₄ and WSi₂N₄) are recently synthesized, theory predicts interesting (opto)electronic properties of a whole new family of such two-dimensional (2D) materials. Here, the chemical trends of band gaps and spin-orbit splittings of bands in selected MSi₂Z₄ (M = Mo, W; Z = N, P, As, Sb) compounds are studied from first-principles. Effective Bethe–Salpeter-equation-based calculations reveal high exciton binding energies. Evolution of excitonic energies under external magnetic field is predicted by providing their effective g-factors and diamagnetic coefficients, which can be directly compared to experimental values. In particular, large positive g-factors are predicted for excitons involving higher conduction bands. In view of these predictions, MSi₂Z₄ monolayers yield a new platform to study excitons and are attractive for optoelectronic devices, also in the form of heterostructures. In addition, a spin-orbit induced bands inversion is observed in the heaviest studied compound, WSi₂Sb₄, a hallmark of its topological nature.     

Zusammenhang zwischen der Ultraschallgeschwindigkeit und den mechanischen Eigenschaften pilzbefallenen Holzes

Ohne Zusammenfassung     

Scalable communication architectures for massively parallel hardware multi-processors

Modern complex embedded applications in multiple application fields impose stringent and continuously increasing functional and parametric demands. To adequately serve these applications, massively parallel multi-processor systems on a single chip (MPSoCs) are required. This paper is devoted to the design of scalable communication architectures of massively parallel hardware multi-processors for highly-demanding applications. We demonstrated that in the massively parallel hardware multi-processors the communication network influence on both the throughput and circuit area dominates the processors influence, while the traditionally used flat communication architectures do not scale well with the increase of parallelism. Therefore, we propose to design highly optimized application-specific partitioned hierarchical organizations of the communication architectures through exploiting the regularity and hierarchy of the actual information flows of a given application. We developed related communication architecture synthesis strategies and incorporated them into our quality-driven model-based multi-processor design methodology and related automated architecture exploration framework. Using this framework we performed a large series of architecture synthesis experiments. Some of the results of the experiments are presented in this paper. They demonstrate many features of the synthesized communication architectures and show that our method and related framework are able to efficiently synthesize well scalable communication architectures even for the high-end massively parallel multi-processors that have to satisfy extremely stringent computation demands.     

Detection of clustered microcalcifications in small field digital mammography

The most frequent symptoms of ductal carcinoma recognised by mammography are clusters of microcalcifications. Their detection from mammograms is difficult, especially for glandular breasts. We present a new computer-aided detection system for small field digital mammography in planning of breast biopsy. The system processes the mammograms in several steps. First, we filter the original picture with a filter that is sensitive to microcalcification contrast shape. Then, we enhance the mammogram contrast by using wavelet-based sharpening algorithm. Afterwards, we present to radiologist, for visual analysis, such a contrast-enhanced mammogram with suggested positions of microcalcification clusters. We have evaluated the usefulness of the system with the help of four experienced radiologists, who found that it significantly improves the detection of microcalcifications in small field digital mammography.     

How to improve the assessment of BPM maturity in the era of digital transformation

For almost 30 years, the way of building business process management maturity models (BPM MMs), the importance assigned to individual maturity levels, and the criteria and critical success factors chosen for BPM maturity assessment have not changed significantly, despite the fact that during those three decades, the business environment and organizations themselves have changed enormously. The impact of hyperautomation and the increasing pace of change require the integration of maturity assessment with the BPM implementation methodology, including the repetition of maturity assessment for selected groups of processes. This causes an urgent need to adapt both process maturity assessment methods and BPM MMs to changing working conditions and business requirements. This conceptual paper is based on a model approach. The framework presented in the article continues and at the same time clearly deviates from the tradition of building BPM MMs on the basis of the Capability Maturity Model (CMM). It proposes a two-stage comprehensive process of organizational process maturity assessment, fully integrated into the process of BPM implementation and further business process management. The presented framework makes it possible to assess the process maturity of Industry 4.0 organizations in which dynamic knowledge-intensive business processes (kiBPs) play a key role in creating value.