Complexity and occupational safety and health prevention research

Society is changing too quickly, both in terms of a shift in the mentality of citizens or employees, and the increasingly frequent appearance of new technologies and new organizations with generally contracting time scales. The new complexity of the work environment modifies occupational safety and health (OSH) research, a paradigm which has to be revisited. Time pressure, complexity and a loss of scientific information have to be taken into account in order to maintain the confidence of the world of work with regard to the possible improvement of the quality of life at work supported by scientific knowledge.     

Lattice,Charge, and Spin Phase Inhomogeneity in Complex-Striped Quantum Matter

The Superstripes 2016 conference, held on June 23–29, 2016, in the island of Ischia in Italy celebrated the 20th anniversary of this series of conferences. For 20 years, structural, electronic, and magnetic phase inhomogeneities in quantum matter have been the scientific focus for a growing physics community interested in complexity in quantum matter. It has been the meeting point for different scientific communities facing the challenging project to unveil the complex space and time landscapes in quantum matter. The interesting spatial inhomogeneity length scale of multiple coexisting phases ranges from atomic to mesoscopic, and the time fluctuations are spread over multiple time scales. The response of these materials changes using different experimental techniques with different spatial and time resolution probing different aspects of the quantum complexity.     

Beyond crystals: the dialectic of materials and information

We argue for a convergence of crystallography, materials science and biology, that will come about through asking materials questions about biology and biological questions about materials, illuminated by considerations of information. The complex structures now being studied in biology and produced in nanotechnology have outstripped the framework of classical crystallography, and a variety of organizing concepts are now taking shape into a more modern and dynamic science of structure, form and function. Absolute stability and equilibrium are replaced by metastable structures existing in a flux of energy-carrying information and moving within an energy landscape of complex topology. Structures give place to processes and processes to systems. The fundamental level is that of atoms. As smaller and smaller groups of atoms are used for their physical properties, quantum effects become important; already we see quantum computation taking shape. Concepts move towards those in life with the emergence of specifically informational structures. We now see the possibility of the artificial construction of a synthetic living system, different from biological life, but having many or all of the same properties. Interactions are essentially nonlinear and collective. Structures begin to have an evolutionary history with episodes of symbiosis. Underlying all the structures are constraints of time and space. Through hierarchization, a more general principle than the periodicity of crystals, structures may be found within structures on different scales. We must integrate unifying concepts from dynamical systems and information theory to form a coherent language and science of shape and structure beyond crystals. To this end, we discuss the idea of categorizing structures based on information according to the algorithmic complexity of their assembly.     

Coherent-array imaging using phased subarrays. Part I: basic principles

The front-end hardware complexity of a coherent array imaging system scales with the number of active array elements that are simultaneously used for transmission or reception of signals. Different imaging methods use different numbers of active channels and data collection strategies. Conventional full phased array (FPA) imaging produces the best image quality using all elements for both transmission and reception, and it has high front-end hardware complexity. In contrast, classical synthetic aperture (CSA) imaging only transmits on and receives from a single element at a time, minimizing the hardware complexity but achieving poor image quality. We propose a new coherent array imaging method--phased subarray (PSA) imaging--that performs partial transmit and receive beam-forming using a subset of adjacent elements at each firing step. This method reduces the number of active channels to the number of subarray elements; these channels are multiplexed across the full array and a reduced number of beams are acquired from each subarray. The low-resolution subarray images are laterally upsampled, interpolated, weighted, and coherently summed to form the final high-resolution PSA image. The PSA imaging reduces the complexity of the front-end hardware while achieving image quality approaching that of FPA imaging.     

Plane-wave-time-domain-enhanced marching-on-in-time scheme for analyzing scattering from homogeneous dielectric structures

A novel and fast integral-equation-based scheme is presented for analyzing transient electromagnetic scattering from homogeneous, isotropic, and nondispersive bodies. The computational complexity of classical marching-on-in-time (MOT) methods for solving time-domain integral equations governing electromagnetic scattering phenomena involving homogeneous penetrable bodies scales as O(NtNs2). Here, Nt represents the number of time steps in the analysis, and Ns denotes the number of spatial degrees of freedom of the discretized electric and magnetic currents on the body's surface. In contrast, the computational complexity of the proposed plane-wave-time-domain-enhanced MOT solver scales as O(NtNs log2Ns). Numerical results that demonstrate the accuracy and the efficacy of the scheme are presented.     

Understanding foods as soft materials

Foods make up some of the most complex examples of soft condensed matter (SCM) with which we interact daily. Their complexity arises from several factors: the intricacy of components, the different aggregation states in which foods are encountered, and the multitude of relevant characteristic time and length scales. Because foodstuffs are governed by the rules of SCM physics but with all the complications related to real systems, the experimental and theoretical approaches of SCM physics have deepened our comprehension of their nature and behaviour, but many questions remain. In this review we discuss the current understanding of food science, by considering established SCM methods as well as emerging techniques and theoretical approaches. With their complexity, heterogeneity and multitude of states, foods provide SCM physics with a challenge of remarkable importance.     

Assessment of manual assembly complexity: a theoretical and empirical comparison of two methods

There are several theoretical methods for assessment of assembly complexity but there are few practically applicable methods. One of the methods, CompleXity Index (CXI), aims at assessing operators’ perception of manual assembly complexity in running production. Another recently developed method, Basic Assembly Complexity (CXB) is intended for predictive assessment of basic manual assembly complexity in early product and production development. Both CXI and CXB aim to improve assembly conditions for operators, reduce assembly-related errors and the costs for corrective measures as well as increase assembly quality although in different ways and at different organisational levels and life cycle stages. The purpose of this study was to compare the two methods to obtain feedback and learn from operators experience in order to develop better predictive assessment criteria. The method comparison showed that about 50% of the CXB assessment approaches were similar to CXI but other covered different aspects. In comparison of the complexity values of the methods no significant results were obtained. However, some CXI issues that were not taken into account in CXB should be considered. CXB and CXI could be used in conjunction but further assessment criteria are probably needed.     

Cyclic oxidation – guidelines for test standardisation,aimed at the assessment of service behaviour†

Abstract

This paper reviews current procedures used for cyclic oxidation testing and their ability to simulate service behaviour for life time prediction modelling. Test complexity varies from a simple laboratory, slow cycle, furnace test to the use of high velocity dynamic combustion rigs. It is shown that the response of an alloy under cyclic oxidation testing varies, depending on the exact test conditions chosen and the length of test exposure, but for many alloy systems this response has common features. It is proposed that all alloys that are protected by a stable, slow growing oxide scale conform to a common, generic behaviour under cyclic oxidation conditions. This life cycle of such alloys involves first the formation of a stable, protective oxide. At a critical thickness this may start to spall, increasing the rate of scale forming element consumption. When the activity of such elements falls below a critical level, in the near surface region, internal oxidation results together with the formation of less protective scales. Ultimately, it is no longer possible for the alloy to self repair following a thermal cycle and then breakaway corrosion ensures, marking the end of the alloys life.

Thus the choice of cyclic test procedure must be tailored to the particular phase of the alloy life cycle under investigation.     

Analysis of fault tolerance and reliability in distributed real-time system architectures

Safety critical real-time systems are becoming ubiquitous in many areas of our everyday life. Failures of such systems potentially have catastrophic consequences on different scales, in the worst case even the loss of human life. Therefore, safety critical systems have to meet maximum fault tolerance and reliability requirements. As the design of such systems is far from being trivial, this article focuses on concepts to specifically support the early architectural design. In detail, a simulation based approach for the analysis of fault tolerance and reliability in distributed real-time system architectures is presented. With this approach, safety related features can be evaluated in the early development stages and thus prevent costly redesigns in later ones.     

The Statistical Evaluation of Categorical Measurements: “Simple Scales,but Treacherous Complexity Underneath”

ABSTRACT

The statistical evaluation of measurements on categorical scales is hampered by hiatuses in insight and conceptualization. Categorical scales have a simple mathematical structure. The underlying empirical reality, however, that they aim to reflect usually has a very complex structure. This complexity induces intricate challenges for the statistical evaluation of the performance of categorical measurement systems. Most current techniques deal ineffectively with these challenges, relying on simplistic conditional independence assumptions and careless sampling strategies. Moreover, they typically evaluate measurement systems in terms of concepts not clearly related to a notion of measurement error. This article proposes an approach for modeling the behavior of categorical measurements based on characteristic curves. The approach is intended to facilitate the development of more effective techniques. It is applied in a case study that illustrates what the authors believe is a realistic degree of complexity.     

Effect of Substrate Wettability and Surface Structure on Nucleation of Crystal

The heterogeneous nucleation behaviors of NH4Cl crystal on rough aluminum substrate surface immerged in NH4Cl-H2O solution were experimentally analyzed, and the influence mechanism of the micro/nano-scale surface structures on heterogeneous nucleation was investigated. It has been shown that wettability and nucleation are affected by substrate surface condition. The intrinsic wetting properties between nucleus and substrate surface, and the surface structure of certain geometrical scales, both impose effects on the heterogeneous nucleation properties. For a nucleus-wetting substrate surface, heterogeneous nucleation is promoted by a higher complexity of the surface morphology; but for a nucleus-nonwetting substrate surface, heterogeneous nucleation is inhibited by a higher complexity of the surface morphology.     

Objects that make objects: the population dynamics of structural complexity.

To analyse the evolutionary emergence of structural complexity in physical processes, we introduce a general, but tractable, model of objects that interact to produce new objects. Since the objects--epsilon-machines--have well-defined structural properties, we demonstrate that complexity in the resulting population dynamical system emerges on several distinct organizational scales during evolution--from individuals to nested levels of mutually self-sustaining interaction. The evolution to increased organization is dominated by the spontaneous creation of structural hierarchies and this, in turn, is facilitated by the innovation and maintenance of relatively low-complexity, but general individuals.     

EBSD and reconstruction of pre-transformation microstructures,examples and complexities in steels

Electron backscattered diffraction has provided a quantitative tool to study micro/nano-structures in large scales. A recent application of electron backscattered diffraction is the reconstruction of pre-transformed phases in polymorphic systems, especially when there is no retained pre-transformed phase at room temperature. This capability has been demonstrated by various researchers utilizing different approaches towards grain structure and orientation recovery. However, parameters affecting reconstruction have not been investigated systematically. Factors such as post-transformed microstructures (morphology and crystallography), lattice strain (deformation), pattern and sample quality are among the affecting factors. Two-dimensional datasets of different steels have been reconstructed along with a limited 3-dimensional dataset in the current paper. Preliminary results intended for large-scale automatic reconstructions have been presented. They indicate that the successfulness of reconstruction is strongly dependent on the post-transformed microstructure. Factors such as morphology, grain size, variant selection, and deformation play roles. Few examples of reconstruction complexity at prior austenite boundaries leading to uncertain results are presented. Lastly, reconstructions are discussed in terms of meaningfulness and if they correctly represent pre-transformed grains and orientations.     

Effects of the curvelet transform over interferometric images

One of the major challenges of the current imaging techniques is to obtain good results from images acquired with interferometric techniques. The huge complexity of these images—presence of numerous negative pixels (～50%), undesired structures introduced by the sparse sampling of the frequencial domain, noise, etc.—advises us to use multiresolution techniques to separate the different problems or features and isolate them in different scales at each resolution level. In this article, we introduce a new tool known as curvelets to work with these images. Its good properties, oriented to classify the visual information in the image depending on its elongated structures, make it an interesting tool to separate the real information from artifacts that belong to the psf sidelobes in different scales. We have decomposed, using both the Wavelet and the Curvelet transform, several interferometric images simulated and acquired with astronomical arrays of radiotelescopes, with which we cover a wide range of situations, and compared each coefficients scale obtained with both transforms. We have found that celestial sources shape keeps better its symmetry in each curvelet scale than in wavelets, and the capability of differentiation between extended sources and point ones is also higher. The identification of the sources is more clear with curvelets as well, because better with curvelets as well because of a high increase of the target enhancement respect the background in the negative pixels of the image. Furthermore, it is possible to create scales with only psf sidelobe information. © 2010 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 20, 333–353, 2010     

Combining Bottom‐Up Self‐Assembly with Top‐Down Microfabrication to Create Hierarchical Inverse Opals with High Structural Order

Colloidal particles can assemble into ordered crystals, creating periodically structured materials at the nanoscale without relying on expensive equipment. The combination of small size and high order leads to strong interaction with visible light, which induces macroscopic, iridescent structural coloration. To increase the complexity and functionality, it is important to control the organization of such materials in hierarchical structures with high degrees of order spanning multiple length scales. Here, a bottom‐up assembly of polystyrene particles in the presence of a silica sol–gel precursor material (tetraethylorthosilicate, TEOS), which creates crack‐free inverse opal films with high positional order and uniform crystal alignment along the (110) crystal plane, is combined with top‐down microfabrication techniques. Micrometer scale hierarchical superstructures having a highly regular internal nanostructure with precisely controlled crystal orientation and wall profiles are produced. The ability to combine structural order at the nano‐ and microscale enables the fabrication of materials with complex optical properties resulting from light–matter interactions at different length scales. As an example, a hierarchical diffraction grating, which combines Bragg reflection arising from the nanoscale periodicity of the inverse opal crystal with grating diffraction resulting from a micrometer scale periodicity, is demonstrated.     

Defining Shape Complexity of Extrusion Dies—A Reliabilistic View

Complexity of the profile being extruded plays a critical role in die design, die reliability, process aberrations, and product defects. Engineering common sense dictates that a more complex die should require a larger amount of extrusion force or pressure. This has been experimentally substantiated by the authors in a recent study. According to a basic definition, therefore, extrusion shape complexity is the ratio of the pressure required to extrude a complex profile to the pressure required for a solid circular profile of the same area. Most of the complexity definitions reported in published literature are based on this interrelationship between extrusion pressure and profile complexity. From a die reliability viewpoint, a complex profile is more difficult to extrude than a simple one, and it generates more stresses in the die. It should therefore lead to an earlier die failure. Another study by the authors confirms that the working life of hot extrusion dies is definitely affected by profile complexity. Reported complexity definitions provide some sort of index to measure extrudability, and can thus be used for pressure prediction to a certain degree. Unfortunately, none of these definitions addresses the very important issue of die reliability, and they generally yield a counterintuitive trend of increasing die life with increasing complexity. None of these definitions includes all the significant geometrical features of a die profile. This article reports the development of two new definitions of shape complexity (linear and power-law) incorporating all significant geometrical features of an extrusion die profile. Die failure data from a large commercial extrusion facility have been collected and analyzed. Regression-based models have been developed for prediction of die failure on the basis of complexity.     

An efficient local improvement operator for the multi-objective wireless sensor network deployment problem

Wireless sensor network layout, also known as sensor node deployment, is a complex NP-complete optimization task that determines most of the functioning features of a wireless sensor network. Coverage, connectivity and lifetime (handled through its opposing parameter, power consumption), are three of the most important characteristics of the service, and are taken into consideration in this article within a multi-objective approach of the problem. Leveraging on the specific properties of the wireless sensor nodes and networks, the Proximity Avoidance Coverage-preserving Operator (PACO) for local improvement is presented, described and tested. The testbed consists of a set of state-of-the-art multi-objective optimization algorithms with different configurations, and problem instances of varying size. In all the scenarios, and more specially in the algorithmic settings that already produce high performance solutions, PACO has proven to be a robust enhancement to the raw optimization technique, without requiring additional computation, that easily scales through problem complexity.     

基于EMD方法的多尺度边缘提取

提出了一个基于EMD方法的多尺度边缘提取方法。利用EMD方法沿水平方向和垂直方向分别处理SAR图像，得到不同尺度的图像。计算不同尺度图像的梯度，得到不同尺度图像的边缘。根据一致性条件，从不同尺度图像的边缘提出SAR图像的边缘。利用这个方法处理了合成孔径雷达图像，成功地提取了图像的边缘信息。