A model for assessing the layout structural complexity of manufacturing systems

The layout of a manufacturing facility/system not only shapes its material flow pattern and influence transportation and operation cost, but also affects logistics and parts/machine assignment decisions. The layout of manufacturing systems determines its structural complexity by virtue of its design configuration characteristics. This paper introduces a new model and indices for assessing the structural complexity of manufacturing systems layout in the physical domain. Six complexity indices, based on the physical structural characteristics of the layout, have been introduced and formulated. They are layout density, path, cycle, decision points, redundancy distribution and magnitude indices. An overall Layout Complexity Index (LCI) which combines all indices is developed using a novel method based on radar plots which is insensitive to the order of plotting the individual indices. The use of the developed LCI is demonstrated using six typical types of manufacturing systems layouts and relevant guidelines are presented. The developed model and complexity indices help design system layouts for least complexity and compare layout alternatives that meet the specifications, at early design stages. It supports making trade-off decisions regarding manufacturing systems flexibility and complexity and their associated costs.     

A generalized “max-min” sample for surrogate update

The preliminary Multidisciplinary Design and Optimisation of a flexible wing aerofoil apropos a small Unmanned Air Vehicle is performed using a multifidelity model-based strategy. Both the passively adaptive structure and the shape of the flexible wing aerofoil are optimised for best aerodynamic performance under aero-structural constraints, within a coupled aeroelastic formulation. A typical flight mission for surveillance purposes is considered and includes the potential occurrence of wind gusts. A metamodel for the high-fidelity objective function and each of the constraints is built, based on a tuned low-fidelity one, in order to improve the efficiency of the optimisation process. Both metamodels are based on solutions of the aeroelastic equations for a flexible aerofoil but employ different levels of complexity and computational cost for modelling aerodynamics and structural dynamics within a modal approach. The high-fidelity model employs nonlinear Computational Fluid Dynamics coupled with a full set of structural modes, whereas the low-fidelity one employs linear thin aerofoil theory coupled with a reduced set of structural modes. The low-fidelity responses are then corrected according to few high-fidelity responses, as prescribed by an appropriate Design of Experiment, by means of a suitable tuning technique. A standard Genetic Algorithm is hence utilised to find the global optimum, showing that a flexible aerofoil is characterised by higher aerodynamic efficiency than its rigid counterpart. Wing weight reduction is also accomplished when a Multiobjective Genetic Algorithm is adopted.     

Eulerian–Lagrangian Simulation and Experimental Validation of Pneumatic Conveying Dryer

This paper explores numerical and experimental studies on the performance of a pneumatic conveying dryer. The four-way coupling Eulerian–Lagrangian approach is utilized in the numerical study and the experimental study is carried out in a pilot-scale vertical pneumatic conveying dryer of diameter 8.1 cm and 4.5 m length. The effects of Reynolds number, particle size, solid mass flow rate, and inlet gas temperature on the dryer performance are investigated. It is found that the present model predictions agree well with the experimental data. Generally, it is concluded that the drying rate increases as the Reynolds number increases, while increasing the particle size or the solid mass flow rate decreases the drying rate.     

Covalent Fragment Screening Identifies Rgl2 RalGEF Cysteine for Targeted Covalent Inhibition of Ral GTPase Activation

Ral GTPases belong to the RAS superfamily, and they are directly activated by K-RAS. The RalGEF pathway is one of the three major K-RAS signaling pathways. Ral GTPases do not possess a cysteine nucleophile to develop a covalent inhibitor following the strategy that led to a K-RAS G12C therapeutic agent. However, several cysteine amino acids exist on the surface of guanine exchange factors that activate Ral GTPases, such as Rgl2. Here, we screen a library of cysteine electrophile fragments to determine if covalent bond formation at one of the Rgl2 surface cysteines could inhibit Ral GTPase activation. We found several chloroacetamide and acrylamide fragments that inhibited Ral GTPase exchange by Rgl2. Site-directed mutagenesis showed that covalent bond formation at Cys-284, but not other cysteines, leads to inhibition of Ral activation by Rgl2. Follow-up time- and concentration-dependent studies of derivatives identified by substructure search of commercial libraries further confirmed Cys-284 as the reaction site and identified the indoline fragments as the most promising series for further development. Cys-284 is located outside of the Ral ⋅ Rgl2 interface on a loop that has several residues that come in direct contact with Ral GTPases. Our allosteric covalent fragment inhibitors provide a starting point for the development of small-molecule covalent inhibitors to probe Ral GTPases in animal models.     

Thermal-induced simultaneous liquid-liquid phase separation and liquid-solid transition in aqueous polyurethane dispersions

Thermal-induced simultaneous phase separation and liquid-solid transition (gelation) in waterborne polyurethane dispersions has been detected morphologically and rheologically. The viscoelastic material functions, such as dynamic shear moduli, G′ and G″ complex shear viscosity, η* and loss tangent, tan δ were found to be very sensitive to the structure evolution during the gelation process and the subsequent formation of a fractal polymer gel. At the onset temperature of the gelation process, an abrupt increase in G′, G″ and η* (several orders of magnitude) was observed during the dynamic temperature ramps (2 °C/min heating-rate) over a wide range of angular frequency. The temperature dependencies of G′, G″ and tan δ were found to be frequency independent at the gel-point, T_gel, providing a fingerprint for determining T_gel of the dispersions. Furthermore, a dramatic increase in zero-shear viscosity, η₀ (v-shape) was observed at T=T_gel and found to be in good agreement with the value obtained from the tan δ versus T data. As expected, the time-temperature-superposition principle was found to be only valid for temperatures lower than the T_gel; the principle failed at T≥70 °C. The morphology of the dispersions at 70 °C for 2 h showed for 36, 38 and 40 wt% formation of a network structure having a unique periodicity and phase connectivity. A lower critical solution temperature (LCST) phase diagram was estimated based on the different morphologies of the dispersions. The coexistence of liquid-liquid and liquid-solid transitions at the same temperature range confirmed the complex behavior of the polyurethane dispersions, pointing to the need for a new theory that explicitly takes this special behavior into account.     

Probing Binding and Cellular Activity of Pyrrolidinone and Piperidinone Small Molecules Targeting the Urokinase Receptor

The urokinase receptor (uPAR) is a cell‐surface protein that is part of an intricate web of transient and tight protein interactions that promote cancer cell invasion and metastasis. Here, we evaluate the binding and biological activity of a new class of pyrrolidinone and piperidinone compounds, along with derivatives of previously‐identified pyrazole and propylamine compounds. Competition assays revealed that the compounds displace a fluorescently labeled peptide (AE147‐FAM) with inhibition constant (K_i) values ranging from 6 to 63 μM . Structure‐based computational pharmacophore analysis followed by extensive explicit‐solvent molecular dynamics (MD) simulations and free energy calculations suggested the pyrazole‐based and piperidinone‐based compounds adopt different binding modes, despite their similar two‐dimensional structures. In cells, pyrazole‐based compounds showed significant inhibition of breast adenocarcinoma (MDA‐MB‐231) and pancreatic ductal adenocarcinoma (PDAC) cell proliferation, but piperidinone‐containing compounds exhibited no cytotoxicity even at concentrations of 100 μM . One pyrazole‐based compound impaired MDA‐MB‐231 invasion, adhesion, and migration in a concentration‐dependent manner, while the piperidinone inhibited only invasion. The pyrazole derivative inhibited matrix metalloprotease‐9 (gelatinase) activity in a concentration‐dependent manner, while the piperidinone showed no effect suggesting different mechanisms for inhibition of cell invasion. Signaling studies further highlighted these differences, showing that pyrazole compounds completely inhibited ERK phosphorylation and impaired HIF1α and NF‐κB signaling, while pyrrolidinones and piperidinones had no effect. Annexin V staining suggested that the effect of the pyrazole‐based compound on proliferation was due to cell killing through an apoptotic mechanism. The compounds identified represent valuable leads in the design of further derivatives with higher affinities and potential probes to unravel the protein–protein interactions of uPAR.     

Experimental Investigation of Newly Synthesized Gemini Cationic Surfactants as Corrosion Inhibitors of Mild Steel in 1.0 M HCl

Three Gemini cationic surfactants named N¹,N¹,N³,N³-tetramethyl-N¹,N³-bis(3-octanamidopropyl) propane-1,3-diaminium bromide (C8-S3-C8), N¹,N¹,N³,N³-tetramethyl-N¹,N³-bis(3-dodecanamidopropyl) propane-1,3-diaminium bromide (C12-S3-C12) and N¹,N¹,N³,N³-tetramethyl-N¹,N³-bis(3-hexadecanamidopropyl) propane-1,3-diaminium bromide (C16-S3-C16) were evaluated as corrosion inhibitors for mild steel in 1.0 M HCl. The corrosion rate of mild steel in 1.0 M HCl at three different temperatures 25, 45 and 60oC was investigated gravimetrically. The corrosion rate of mild steel was confirmed electrically at 25oC. The corrosion inhibition efficiency directly proportionally with the hydrophobic chain length of inhibitors. The inhibition efficiency exhibit a positive trend with raising the solution temperatures. The potentiostatic polarization study revealed that the tested gemini cationic surfactants act as mixed type inhibitors with predominant control of cathodic reaction. The Villamil isotherm provide the best describing of the adsorption process on the selected steel in 1.0 M HCl. The adsorption of the tested inhibitors on the steel surface is a mixture of chemical and physical adsorption.     

Mass production of CNTs using CVD multi-quartz tubes

Carbon nanotubes (CNTs) have become the backbone of modern industries, including lightweight and heavy-duty industrial applications. Chemical vapor deposition (CVD) is considered as the most common method used to synthesize high yield CNTs. This work aims to develop the traditional CVD for the mass production of more economical CNTs, meeting the growing CNT demands among consumers by increasing the number of three particular reactors. All reactors housing is connected by small channels to provide the heat exchange possibility between the chambers, thereby decreasing synthesis time and reducing heat losses inside the ceramic body of the furnace. The novel design is simple and cheap with a lower reacting time and heat loss compared with the traditional CVD design. Methane, hydrogen, argon, and catalyzed iron nanoparticles were used as a carbon source and catalyst during the synthesis process. In addition, CNTs were produced using only a single quartz tube for comparison. The produced samples were examined using XRD, TEM, SEM, FTIR, and TGA. The results showed that the yield of CNTs increases by 287 % compared with those synthesized with a single quartz tube. Moreover, the total synthesis time of CNTs decreases by 37 % because of decreased heat leakage.

     

Log-based transactional workflow mining

A continuous evolution of business process parameters, constraints and needs, hardly foreseeable initially, requires a continuous design from the business process management systems. In this article we are interested in developing a reactive design through process log analysis ensuring process re-engineering and execution reliability. We propose to analyse workflow logs to discover workflow transactional behaviour and to subsequently improve and correct related recovery mechanisms. Our approach starts by collecting workflow logs. Then, we build, by statistical analysis techniques, an intermediate representation specifying elementary dependencies between activities. These dependencies are refined to mine the transactional workflow model. The analysis of the discrepancies between the discovered model and the initially designed model enables us to detect design gaps, concerning particularly the recovery mechanisms. Thus, based on this mining step, we apply a set of rules on the initially designed workflow to improve workflow reliability. The work presented in this paper was partially supported by the EU under the SUPER project (FP6-026850) and by the Lion project supported by Science Foundation Ireland under Grant No. SFI/02/CE1/I131.