Verifying the accuracy of interlocking tables for railway signalling systems using abstract state machines

Railway transportation system is a critical sector where design methods and techniques are defined by international standards in order to reduce possible risks to an acceptable minimum level. CENELEC 50128 strongly recommends the utilization of finite state machines during system modelling stage and formal proof methods during the verification and testing stages of control algorithms. Due to the high importance of interlocking table at the design state of a signalization system, the modelling and verification of interlocking tables are examined in this work. For this purpose, abstract state machines are used as a modelling tool. The developed models have been performed in a generalized structure such that the model control can be done automatically for the interlocking systems. In this study, NuSMV is used at the verification state. Also, the consistency of the developed models has been supervised through fault injection. The developed models and software components are applied on a real railway station operated by Metro Istanbul Co.

     

An analysis of the gamma memory in dynamic neural networks

Presents a vector space framework to study short-term memory filters in dynamic neural networks. The authors define parameters to quantify the function of feedforward and recursive linear memory filters. They show, using vector spaces, what is the optimization problem solved by the PEs of the first hidden layer of the single input focused network architecture. Due to the special properties of the gamma bases, recursion brings an extra parameter lambda (the time constant of the leaky integrator) that displaces the memory manifold towards the desired signal when the mean square error is minimized. In contrast, for the feedforward memory filter the angle between the desired signal and the memory manifold is fixed for a given memory order. The adaptation of the feedback parameter can be done using gradient descent, but the optimization is nonconvex.     

A Model for Efficient Consumer Pricing Schemes in Electricity Markets

Suppliers in competitive electricity markets regularly respond to prices that change hour by hour or even more frequently, but most consumers respond to price changes on a very different time scale, i.e., they observe and respond to changes in price as reflected on their monthly bills. In this paper, we examine mixed complementarity programming models of equilibrium that can bridge the speed of response gap between suppliers and consumers yet adhere to the principle of marginal cost pricing of electricity. We develop a computable equilibrium model to estimate ex ante time-of-use (TOU) prices for a retail electricity market. It is intended that the proposed models would be useful 1) for jurisdictions (e.g., Ontario) where consumers' prices are regulated, but suppliers offer into a competitive market, 2) for forecasting forward prices in unregulated markets, and 3) in evaluation and welfare analysis of the policies regarding regulated TOU pricing compared to regulated single pricing     

Integrating mobile multimedia into textbooks: 2D barcodes

The major goal of this study was to empirically compare text-plus-mobile phone learning using an integrated 2D barcode tag in a printed text with three other conditions described in multimedia learning theory. The method examined in the study involved modifications of the instructional material such that: a 2D barcode was used near the text, the learner scanned the tag with the camera on his/her mobile phone and reached the animation and narration on the mobile phone's screen. Using this method, we created a new approach that reinforces printed textbooks, which had the poorest retention and transfer results. The results suggest that supporting a printed textbook with camera-equipped mobile devices and 2D barcodes linked to supplemental information, may increase the effectiveness of learning.     

Indoor radon concentrations in Adana, Turkey

The indoor radon concentration in Adana, Turkey was measured in living rooms of 52 houses during winter 2005 and 57 houses during summer 2005. Forty-four houses were selected for both winter and summer researches for estimating seasonal variations. Indoor radon concentrations were measured seasonally over hotter and colder 2 months over the whole year, using CR-39 passive nuclear track radon detectors. The radon concentrations were ranged from 15 to 97 Bq m(-3) on January-February 2005 for 60 d and from 5 to 70 Bq m(-3) on June-July 2005 for 60 d. The average summer concentration measured was 25.8 Bq m(-3) and the average winter concentration was 48.9 Bq m(-3) in 44 houses that observed seasonal variations. The differences between winter and summer periods were ranged from 1 to 77 Bq m(-3). The average value in both winter and summer periods is 37 Bq m(-3) in 44 houses that observed seasonal variations. This value is below the worldwide indoor radon concentration distribution of 46 Bq m(-3). The annual effective dose equivalent from (222)Rn was 0.9 mSv y(-1).     

Combined effect of a plasticizer and carvacrol and thymol on the mechanical,thermal, morphological properties of poly(lactic acid)

In this study, the effects of the monotherpenic phenol concentration on the properties of biocomposites containing plasticized poly(lactic acid) (PLA) with acetyl tributyl citrate (ATBC) were investigated. The monotherpenic phenols carvacrol (C) and thymol (T) were added to PLA by a melt‐blending method. The prepared samples were characterized by means of tensile testing, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy (SEM), and antibacterial activity tests. The addition of ATBC to PLA resulted in hydrogen bonding between ATBC and PLA. We observed that ATBC, C, and T reduced the glass‐transition temperature of PLA. The presence of C and T decreased the maximum degradation temperature slightly. Because of the plasticization effect of the additives, the tensile strength and Young's modulus of PLA decreased, whereas the extent of elongation they experienced before failure increased. This effect was also observed with SEM analysis in terms of plastic deformation at break. The antibacterial activity tests showed that samples containing high concentrations of C demonstrated an improved antibacterial activity against Staphylococcus aureus, Salmonella typhimurium, and Listeria monocytogenes bacteria. We observed that C exhibited a higher inhibition against bacterial strains than T. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45895.     

Thermal stress analysis of functionally graded annular fin

Thermal stress distributions in an annular fin with rectangular profile made of functionally graded material (FGM) are considered. The material properties of annular fin are assumed to be graded along the fin radius as a power-law function while the Poisson’s ratio is taken to be constant. The governing equations are solved analytically for specific value of inhomogeneity parameter of thermal conductivity and all numerical values of inhomogeneity parameters of modulus of elasticity and linear thermal expansion coefficient. The effect of the inhomogeneity parameters on temperature distribution and thermal stresses are presented in graphical form. The formulation is validated with benchmark results in the literature. It is also shown that functionally graded annular fin is subject to lower stresses, although it has higher tip temperature than the homogeneous one.     

N-alkylpiperidine·alane compounds and their applications in alane regeneration

The synthesis, characterization, and detailed thermal properties of N-alkylpiperidine·alane compounds are described. Direct reaction of 1 equiv of N-alkylpiperidine (NMPi or NEPi, NMPi = N-methylpiperidine, NEPi = N-ethylpiperidine) with 1 equiv of γ-AlH₃ readily gives the 1:1 adduct NMPi·AlH₃ (or NEPi·AlH₃) in good yields and purity. Attempts to prepare the related 2:1 complexes were unsuccessful; however, in situ studies by infrared spectroscopy showed the formation of (NMPi)₂·AlH₃ when a large excess of NMPi was present, whereas no (NEPi)₂·AlH₃ was observed under similar conditions. Such difference in reactivity is due to the steric effect of the ethyl group in NEPi. Under heat and vacuum, both NMPi·AlH₃ and NEPi·AlH₃ react with 1 equiv of LiH to form non-solvated LiAlH₄ in nearly quantitative yields. However, they display dramatically different decomposition pathways without LiH or with a catalytic amount of LiH. While NMPi·AlH₃ decomposes to Al metal directly, NEPi·AlH₃ can be selectively decomposed to form AlH₃ under certain conditions. Moreover, the transamination of (NMPy)₂·AlH₃ (NMPy = N-methylpyrrolidine) with NEPi has been shown to give NEPi·AlH₃ in good yields. Compared to Et₃N, NEPi not only extends the scope of the transamination to include a wide range of amine·alane adducts, but also improves the yield, selectivity, and energy-efficiency of the process. Combining these results with the formation of (NMPy)₂·AlH₃ via hydrogenation, we have established an improved regeneration pathway for AlH₃ using NMPy, NEPi, and Al metal.     

Effect of particle size on microstructural and mechanical properties of UHMWPE–TiO2 composites produced by gelation and crystallization method

In this study, Ultra-high-molecular-weight polyethylene (UHMWPE) in 0.5 wt % concentration—0.5, 1, and 2 wt % nanosized and micron-sized TiO₂ composites were produced via gelation/crystallization method in decalin + antioxidant solution at 150 °C for 45 min by using magnetic stirrer. The gel composites were cooled in an aluminum tray embedded in iced water under ambient conditions and dried in an oven at 130 °C for 90 min to remove any residual trace of decalin and to strengthen the UHWMPE matrix. Scanning electron microscopy–EDS images indicate that TiO₂ particles were integrated well with the polymer matrix. differential scanning calorimetry studies revealed that the crystallinity of pure UHMWPE was calculated as 56% and an increase of 13.32% for micron sized and 19.25% for nano sized TiO₂. Crystalline and amorphous phases of UHMWPE–TiO₂ composites confirmed by Raman are in good agreement with the literature. The elastic modulus of test materials ranged from 610 to 791 MPa for micron sized and raised from 675 to 1085 for nano sized reinforcing agents. Ultimate tensile stress increased about 35% for micron sized and 60% for nano sized weight 1% TiO₂ reinforced composites. Biomineralization tests (performed in stimulated body fluid, at 37 °C and 6.5 pH during 1 month) have shown that produced composites are compatible as acetabular liner replacement for hipjoints due to no accumulation (Ca, P, Na, etc.) on UHMWPE–TiO₂ composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47402.     

Investigation of Boronizing Kinetics of AISI 51100 Steel

In this study, some mechanical properties of borided AISI 51100 steel with high C concentration were investigated. Boronizing heat treatment was carried out in solid medium consisting of Ekabor-II at 850, 900, and 950 °C for 2, 4, 6, and 8 h. Morphology and mechanical properties of boride layer, and the effect of chemical composition on properties and kinetics of borides were investigated. The results of this study indicated that the morphology of the boride layer has a saw-tooth nature, and its hardness is over 1500 HV. Depending on process time and temperature, the depth of boride layer ranged from 30 to 106 μm. Optical and SEM studies and XRD analysis revealed that borides formed on the surface of steel substrates have dominantly single Fe₂B boride phase in addition to small amount of Cr₂B.