A practical data-flow verification scheme for business processes

Data in business processes becomes more and more important. Current standard languages for process modeling like BPMN 2.0 which include the data flow reflect this. Ensuring the correctness of the data flow in processes is challenging. Model checking, i.e., verifying properties of process models, is a well-known technique to this end. An important part of model checking is the construction of the state space of the model. However, state-space explosion typically is in the way of an effective verification. We study how to overcome this problem in our context by means of reduction. More specifically, we propose a reduction on the level of the process model. To our knowledge, this is new for the data-flow analysis of processes. The core of our approach are so-called regions of the process model that are relevant for the verification of properties describing the data flow. Non-relevant regions are candidates for reduction of the process model, yielding a smaller state space. Our evaluation shows that our approach works well on industrial process models.     

Order-of-addition experiments: A review and some new thoughts

Abstract

The study of order-of-addition (OofA) experiments is prevalent in many scientific and industrial areas. The statistical design of experiments (DOE) will considerably improve the efficiency of OofA experiments. Designing and modeling the OofA experiments have increasingly received a great deal of attention. In this article, we review the latest work on the design and model of OofA experiments, and introduce some new thoughts. We believe that this article will motivate fruitful applications in real OofA experiments as well as future developments in the methodology.     

Roles of calcium-containing alkali materials on dark fermentation and anaerobic digestion: A systematic review

The accelerated chemical-industry has caused a rapid increase of calcium-containing alkali wastes, containing a large amount of calcium, magnesium, aluminum, and iron ions and caused a great risk to environment. Anaerobic digestion or dark fermentation is one of the most promising technologies to recover biogas, such as methane and hydrogen. Nevertheless, the hydrolysis processes of lignocellulosic biomass and waste activated sludge were the rate-limiting step of the biochemical reactions, which focused on pretreatment to improve the biodegradability of substrate. In addition, when some easily acidified wastes, such as kitchen residue, fruit and vegetable waste, and high concentration organic wastewater, are used as substrate to produce hydrogen and methane, volatile fatty acid accumulation often occurs, causing the process instability. Thus, this paper reviewed the main roles of calcium-based alkali materials such as calcium oxide, calcium peroxide and calcium hydroxide on the substrate pretreatment for obtaining high biodegradability, while others (e.g. calcium carbonate, lime and red muds) used as additives for maintaining process stability, thereby increasing biogas yield from anaerobic digestion and dark fermentation.     

Fluidisation characteristics of granular activated carbon in drinking water treatment applications

Granular activated carbon (GAC) filtration is an important unit operation in drinking water treatment. GAC filtration is widely used for its filtration and adsorption capabilities as a barrier for undesired organic macro- and micro-pollutants. GAC filtration consists of two successive phases: adsorption and filtration, capturing the impurities from the water in conjunction with a backwash procedure in which the suspended particles are flushed out of the system. Available literature predominantly focusses on adsorption. A less frequently discussed but nevertheless equally crucial aspect of this operation is the backwash procedure of GAC beds. To prevent accumulation of suspended particles and to avoid additional operation costs, optimal backwashing is required. Another factor is sustainability: water utilities are showing increasing interest in exploring new sustainable GAC media. As these have different bed expansion tendencies due to different GAC characteristics with varying geometries, operational developments are needed for prediction models to estimate the expansion degree during backwashing. The prediction of the bed expansion of GAC is complex as the particles are non-spherical, porous and polydisperse. Through a combination of advanced particle laboratory and fluidisation experiments, we demonstrate a new approach which leads to an improved expansion prediction model for the backwashing of GAC filters.     

Predicting dust emissions – Experimental study compared to coupled DEM/CFD simulations using a reference test bulk material

The awareness of dust emissions is crucial regarding safe industrial processes, environmental protection and health care. For this purpose, closely linked experimental and numerical investigations are performed. This work presents the results of an experimental study which is used for the calibration of a modelling framework based on the Discrete Element Method (DEM) coupled with Computational Fluid Dynamics (CFD) and applied for the calculation of dust emissions for predictive purposes. The key objective of the approach is to come up with a dust source term which enables to describe and to quantify the release of particle emissions. For the presented experimental study, a wind tunnel and a rotating drum setup, which cover various handling types of bulk materials, are used in order to gain data about parameters having an impact on the dust release. The special feature of the investigations is the use of a reference test bulk material which represents a bulk material in its generally main fractions, the fine and the coarse material, keeping the discrepancy between experiments and simulations low. With the help of the experimental results the calibration of the simulation model was carried out and followed by a comparison.     

Impact of precursor preparation on density of gadolinium iron garnets synthesized via reactive sintering

Gadolinium iron garnet was obtained from two different precursors, homogenized in isopropyl alcohol and in an aqueous environment with a fixed pH. In the first case, it was a mixture of goethite (FeO(OH)) and gadolinium oxide (Gd₂O₃); in the second, a mixture of GdIP (GdFeO₃) and α-Fe₂O₃. Conditions of homogenization in the aqueous environment were selected based on the zeta (ξ) potential measurements as the function of pH. DSC measurements of the output powder mixtures allowed the identification of the effects observed during the temperature rise. In the case of the material obtained from a mixture of goethite (FeO(OH)) and gadolinium oxide, with the increasing temperature, we observe three effects, the first of which corresponds to the phase transformation of goethite into α-Fe₂O₃, the second corresponds to the reaction of gadolinium iron perovskite (GdIP) formation, and the third to the reaction in which a gadolinium iron garnet (GdIG) is formed. However, in the case of heat treatment of the mixture of GdIP and α-Fe₂O₃, we only observe the effect responsible for a solid state reaction leading to the formation of gadolinium iron garnet. Dilatometric measurements allowed to determine the changes in linear dimensions at various stages of reaction sintering. The resulting materials were sintered at temperatures of 1200, 1300, and 1400 °C. In the case of the material obtained from a mixture of perovskite and iron (III) oxide, already at the temperature of 1300 °C, a density has been obtained at around 95% of the theoretical density, and the temperature of 1400 °C allowed achieving a density of 97% of the theoretical density. Whereas, for the material obtained from a mixture of goethite (FeO(OH)) and gadolinium oxide, a density above 95% of theoretical density was achieved only at 1400 °C.     

Poly(2,5-Dihydroxy-1,4-Benzoquinonyl Sulfide) As an Efficient Cathode for High-Performance Aqueous Zinc–Organic Batteries

Aqueous rechargeable zinc-ion batteries (ZIBs) have attracted considerable attention as a promising candidate for low-cost and high-safety electrochemical energy storage. However, the advancement of ZIBs is strongly hindered by the sluggish ionic diffusion and structural instability of inorganic metal oxide cathode materials during the Zn²⁺ insertion/extraction. To address these issues, a new organic host material, poly(2,5-dihydroxy-1,4-benzoquinonyl sulfide) (PDBS), has been designed and applied for zinc ion storage due to its elastic structural factors (tunable space and soft lattice). The aqueous Zn-organic batteries based on the PDBS cathode show outstanding cycling stability and rate capability. The coordination moieties (O and S) display the strong electron donor character during the discharging process and can act as the coordination arms to host Zn²⁺. Also, under the electrochemical environment, the malleable polymer structure of PDBS permits the rotation and bending of polymer chains to facilitate the insertion/extraction of Zn²⁺, manifesting the superiority and uniqueness of organic electrode materials in the polyvalent cation storage. Finally, quasi-solid-state batteries based on aqueous gel electrolyte demonstrate highly stable capacity under different bending conditions.     

Piezoelectricity of the Transmembrane Protein ba3 Cytochrome c Oxidase

Controlling the electromechanical response of piezoelectric biological structures including tissues, peptides, and amino acids provides new applications for biocompatible, sustainable materials in electronics and medicine. Here, the piezoelectric effect is revealed in another class of biological materials, with robust longitudinal and shear piezoelectricity measured in single crystals of the transmembrane protein ba₃ cytochrome c oxidase from Thermus thermophilus. The experimental findings from piezoresponse force microscopy are substantiated using a range of control measurements and molecular models. The observed longitudinal and shear piezoelectric responses of ≈ 2 and 8 pm V⁻¹, respectively, are comparable to or exceed the performance of commonly used inorganic piezoelectric materials including quartz, aluminum nitride, and zinc oxide. This suggests that transmembrane proteins may provide, in addition to physiological energy transduction, technologically useful piezoelectric material derived entirely from nature. Membrane proteins could extend the range of rationally designed biopiezoelectric materials far beyond the minimalistic peptide motifs currently used in miniaturized energy harvesters, and the finding of robust piezoelectric response in a transmembrane protein also raises fundamental questions regarding the molecular evolution, activation, and role of regulatory proteins in the cellular nanomachinery, indicating that piezoelectricity might be important for fundamental physiological processes.     

Chemical bond characteristics and infrared reflectivity spectrum of a novel microwave dielectric ceramic CaIn2O4 with near-zero τf

Orthorhombic-structured CaIn₂O₄ ceramics with a space group Pca2₁ were synthesized via a solid-state reaction method. A high relative density (95.6 %) and excellent microwave dielectric properties (ε_r ～11.28, Qf = 74,200 GHz, τ_f ～ ?4.6 ppm/°C) were obtained when the ceramics were sintered at 1375 °C for 6 h. The dielectric properties were investigated on the basis of the Phillips–Van Vechten–Levine chemical bond theory. Results indicated that the dielectric properties were mainly determined by the InO bonds in the CaIn₂O₄ ceramics. These bonds contributed more (74.65 %) to the dielectric constant than the CaO bonds (25.35 %). Furthermore, the intrinsic dielectric properties of the CaIn₂O₄ ceramics were investigated via infrared reflectivity spectroscopy. The extrapolated microwave dielectric properties were ε_r ～10.12 and Qf = 112,200 GHz. Results indicated that ion polarization is the main contributor to the dielectric constant in microwave frequency ranges.     

Thermodynamic modelling of the ternary Bi-Ga-Te system for potential application in thermoelectric materials

Thermoelectric materials have drawn widespread attention because they can enable the direct conversion between electric and thermal energy. Over the years, different materials such as skutterudites, clathrates, intermetallic alloys, eutectic alloys, chalcogenides have been explored for Thermoelectric (TE) applications. Amongst the eutectic alloys, the Bi-Ga-Te system exhibits promising potential as a TE material. Accordingly, in this study, we performed the thermodynamic optimization and critical evaluation of binary Bi–Ga, Bi–Te, Ga–Te, and ternary Bi-Ga-Te systems using the CALPHAD method. It is observed that the Ga–Te system shows asymmetric liquid solution properties with strong negative enthalpy of mixing, whereas the Bi–Te liquid exhibits the symmetric regular solution behavior. Moreover, the Bi–Ga liquid solution has a positive enthalpy of mixing. Therefore, Modified Quasichemical Model (MQM) using pair approximation was utilized to describe the diversified thermodynamic properties of liquid solution in sub-binaries by taking into account the Short-Range Ordering (SRO). By merging the binary optimization results with a proper interpolation method, the liquid solution properties and phase diagram information in the Bi-Ga-Te ternary system were also reproduced successfully without any adjustable ternary parameter. Several ternary eutectic compositions were suggested for designing TE alloy with enhanced properties using the developed database.