S-shaped Transition Research Articles

Enhancing Accuracy and Consistency in the Valuation of Plant and Equipment through Cubic Regression Models of Physical Deterioration

The valuation of plant and equipment often involves valuers deducting physical, functional and economic depreciation from replacement cost estimates. These calculations have faced accuracy and consistency problems in the aspect of determining how much physical deterioration should be deducted. This study attempted to develop cubic regression models to resolve these accuracy and consistency problems in the basic metal, iron and steel and fabricated metal product sectors in Ogun state, Nigeria (Sango Ota and Agbara). Questionnaire surveys were administered on senior operators of plant and equipment in these sectors to draw information on the degree of physical deterioration of plant and equipment over service life, using expenditure on repairs as a proxy for physical deterioration. The questionnaire sought information on the service lives of plant and equipment, the pattern of physical depreciation over the service lives, and the degree to which the pattern is influenced by various operational factors. Data were analysed using means, standard deviations, multiple linear regressions and cubic regressions, to produce what could be the first potentially accurate and consistent valuation model of physical deterioration in Africa. The service lives of various plant and equipment were found to range at various times between 8 to 60 years. Cubic regression analyses showed that the pattern of the movement of transitions of expenditure on repairs (proxy for physical deterioration) over useful life of plant and equipment were not linear but cubic, and generally followed S-shaped patterns. Multiple regression analyses showed that the S-shaped patterns were in turn influenced by operational factors (such as intensity of use and power outages). The study concluded that valuers’ interests in accuracy and consistency in plant and equipment valuation were not served by any of the accounting methods hitherto used by valuers; accuracy in physical deterioration modelling follows an S-shaped transition over time.

S-shaped transition trajectory and dynamic development frontier of the financial systemic risk research: a multiple networks analysis

Financial systemic risk has an impact on the real economy and may trigger a chain reaction in the whole economic system leading to the financial crisis. Many scholars focus on financial systemic risk, but few of them are bibliometric analyses. Therefore, this paper explores the status quo, emerging trends, and transition trajectory through the above analysis method in the research field from 1990 to 2020. Based on the above analysis, we find the following conclusions: (1) The basic conclusions of the most productive countries, institutions, journals, authors, status quo, and the change of hotspots in this research field are presented. (2) The emerging trends in this research field are ‘credit risk’, ‘capital shortfall’, ‘spill-over’, ‘spread’, ‘financial market’, ‘interconnectedness’, ‘transmission’ in the last three years. (3) The research field of financial systemic risk presents an S-shaped transition trajectory through the local forward, the local backward, the global standard, and the global key-route main path analysis. (4) We find that the most cited authors are not always at the core of the trajectory of financial systemic risk research. The emerging trend ‘credit risk’ is also recently a core research direction in this research field’s transition trajectory.

A Nanoboat with Fused Concave N-Heterotriangulene.

The surface extension of all-carbon based bowl-shaped molecules, such as corannulene and sumanene, to synthesize even larger buckybowls has been widely studied, leaving other concave compounds with heteroatoms less considered. Herein we present a highly curved molecule synthesized via stepwise cyclization of fjords of a bisacridone derivative. Crystallographic analysis unambiguously confirmed a boat-shaped structure with deformed bottom benzene ring. Theoretical calculation unravels an inversion process with an S-shaped transition structure rather than a planar one. The enlarged boat demonstrates interesting properties, such as red shifts in absorption and emission spectra, enhanced emission intensity, and convergent frontier molecular orbital energy levels, in comparison to the related concave N-heterotriangulene.

Design optimization of S-shaped compressor transition duct using particle swarm optimization algorithm

A high-bypass turbofan engine transfers air from low- to the high-pressure compressor through an S-shaped transition duct. Minimization of the total pressure loss and maximization of uniform flow are key factors to ensure the maximum performance of the S-shaped transition duct. The conventional design approach is time-consuming and does not guarantee an optimal solution. Hence, the present article is based on the application of optimization for the S-shaped compressor transition duct. The optimization is carried out on the basis of shape parameters to minimize objectives namely pressure loss coefficient and non-uniformity with the reduction of length of the S-shaped transition duct. The 2-D axisymmetric approach of computational fluid dynamics is used as a design tool for performance evaluation with optimization techniques. The simulation model is validated with the available experimental results of the literature. The correlation between the response and independent variables is established with the help of the second-order polynomial response surface methodology. Further, individual optimization is carried out for single-objective consideration using particle swarm optimization and gray wolf optimization algorithms. As the results of single-objective optimization depict the conflicts between both objectives, later optimization using multi-objective particle swarm optimization and multi-objective gray wolf optimization algorithms is carried out. The performance metrics are obtained and compared. The ‘TOPSIS’ method is applied to get best solution out of multiple solutions. The optimized duct reduced pressure loss coefficient and non-uniformity index by 28.14% and 43.33% with a reduction of 6.37% of length compared to baseline S-shaped duct.

S-Shaped Transition Curves as an Element of Reverse Curves in Road Design

A road designing involves horizontal and vertical alignment. The horizontal geometry is formed by straight and curvilinear sections that are traditionally formed using circular and transition curves (mainly the clothoid). Different geometric systems that are designed using circular and transition curves are between others circular curves with symmetrical or unsymmetrical clothoids, combined curves, oval curves and reverse curves. Designing these systems is quite complex. Therefore, so-called S-shaped transition curves are an alternative to traditional approaches. These curves are known from literature and are modern geometric tools for the shaping of reverse curves. The paper analyses the basic geometric properties of these curves as well as compare to the geometry of the appropriate geometric systems, which are formed with clothoid or using S-shaped transition curves. In addition, a procedure for designing reverse curves using S-shaped transition curves was proposed. Another research topic was the comparison of the analysed reverse curves (created using polynomial transition curves) with traditional curves (created using the clothoid). The results of the studies, despite the noticeable differences in the geometry of the compared components, confirm the practical usefulness of the S-shaped transition curves for designing the geometry of the route.

Design optimization of a compressor transition S-shaped duct using a teaching–learning-based optimization algorithm

A high bypass turbofan aero-engine delivers compressed air from the low-pressure to the high-pressure compressor through a compressor transition duct. Weight and design space limitations impel to its S-shaped design. Despite that, the compressor transition duct has to guide the flow very carefully to the high-pressure compressor without disturbances and flow separations. Hence, the present paper is devoted to elaborate on the application of the proposed heuristic optimization technique known as multi-objective teaching–learning-based optimization (MO-TLBO) algorithm in the area of S-shaped transition compressor duct. The present algorithm is applied for obtaining the optimum design of the S-shaped duct while minimizing the total pressure loss coefficient and non-uniformity index at the S-shaped duct outlet. These objectives are also optimized independently and as a multi-objective consideration as well. Because of the conflicting nature of the objective functions, a Pareto-optimal curve is also presented for a successful trade-off between the objectives. Pareto-optimal curve gives flexibility to the designer for selecting the best set of the parameters based on the objectives. Successful execution of the proposed MO-TLBO algorithm is examined by comparing the optimum results acquired by the multi-objective genetic algorithm and comparisons divulge that the TLBO algorithm can be successfully practiced to obtain the optimized design of compressor transition S-shaped duct. Optimized duct shows the reduction in total pressure loss and non-uniformity by 28.80% and 36.67%, respectively, despite the reduction of 14.74% in overall length.

Influence of Backward- and Forward-Facing Steps on the Flow Through a Turning Mid Turbine Frame

For this work, reality effects, more precisely backward-facing steps (BFSs) and forward-facing steps (FFSs), and their influence on the flow through a two-stage two-spool turbine rig under engine-relevant conditions were experimentally investigated. The test rig consists of an high pressure (HP) and an low pressure (LP) stage, with the two rotors rotating in opposite direction with two different rotational speeds. An S-shaped transition duct, which is equipped with turning struts (so-called turning mid turbine frame (TMTF)) and making therefore a LP stator redundant, connects both stages and leads the flow from a smaller to a larger diameter. This test setup allows the investigation of a TMTF deformation, which occurs in a real aero-engine due to non-uniform warming of the duct during operation—especially during run up—and causes BFSs and FFSs in the flow path. This happens for nonsegmented ducts, which are predominantly part of smaller engines. In the case of the test rig, steps were not generated by varying temperature but by shifting the TMTF in horizontal direction while the rotor and its casing were kept in the same position. In this way, both BFSs and FFSs between duct endwalls and rotor casing could be created. In order to avoid steps further downstream of the interface between HP rotor and TMTF, the complete aft rig was moved laterally too. In this case, the aft rig incorporates among others the LP rotor, the LP rotor casing, and the deswirler downstream of the LP stage. In order to catch the influence of the steps on the whole flow field, 360 deg rake traverses were performed downstream of the HP rotor, downstream of the duct, and downstream of the LP rotor with newly designed, laser-sintered combi-rakes for the measurement of total pressure and total temperature. Only the compact design of the rakes, which can be easily realized by additive manufacturing, makes the aforementioned 360 deg traverses in this test rig possible and allows a number of radial measurements positions, which is comparable to those of a five-hole probe. To get a more detailed information about the flow, also five-hole probe measurements were carried out in three measurement planes and compared to the results of the combi-rakes.

On control polygons of Pythagorean hodograph septic curves

For a given septic Bézier curve with a distinct ordered sequence of control points, how to determine whether it is a PH curve via exact symbolic computation in theory. This problem motivated the study of a necessary and sufficient condition for a planar septic Bézier curve to possess a Pythagorean hodograph (PH). Based on the definition of a PH curve and the complex representation of a planar curve, we develop geometric conditions in terms of the leg-lengths and angles of a control polygon that must be separated to guarantee the PH property. The relation between the compatibility of solutions with respect to the complex coefficients of PH equations and geometric constraints is analyzed. Moreover, PH septic curves with inflections are extended to construct S-shaped transition curves.

A combinatorial optimization design method applied to S-shaped compressor transition duct design

This paper presents a combinatorial optimization method based on uniform design in combination with response surface methodology and genetic algorithm. Uniform design is used to obtain experimental points and response surface methodology to establish a mathematical regression model. Subsequently, genetic algorithm is employed to acquire optimal solution of the objective function. The optimization method has been applied to a two-dimensional S-shaped transition duct design. The process is performed with two design variables. One defines the drop height ratio which describes wall profile, and the other depicts the length ratio between the axial length of the S-shaped transition duct and the duct inlet height. Total pressure loss coefficient as an aerodynamic performance parameter is selected as the objective function for optimization. The objective function is numerically assessed at design points sampled by uniform design in the experimental domain. The initial transition duct was designed with a radius-change to length ratio 11.6% larger than current engine design limits, and the optimization yields a decrease of 36.9% in total pressure loss and more uniform distributions of parameters at the outlet. The paper shows that the described optimization method can be applied to turbofan engines to increase the radial offset and decrease the axial design space between the fans and cores without jeopardizing performance.

Synthetic and structural considerations on highly curved bowl-shaped fragments of fullerenes

AbstractNumerous highly curved fragments of C60 and unique subunits of C70 were synthesized under mild conditions using metal-catalyzed protocols. According to X-ray crystallographic analyses, highly curved fragments of C60 have a maximum π-orbital axis vector (POAV) pyramidalization angle of up to 12.9 °, whereas distinctive fragments of C70, analogous to the tube portion of the rugby-shaped buckyball, are less curved. Among the eight buckybowls studied herein, five form polar crystals. Depending on the molecular geometry, the inversion dynamics of buckybowls involves either a planar or an S-shaped (non-planar) transition structure.

Highly Curved Bowl‐Shaped Fragments of Fullerenes: Synthesis, Structural Analysis, and Physical Properties

Highly curved buckybowls 3, 4, and 5 were synthesized from planar precursors, fluoranthenes 8, benzo[k]fluoranthenes 10 and naphtho[1,2-k]-cyclopenta[cd]fluoranthenes 12, respectively, using straightforward palladium-catalyzed cyclization reactions. These fluoranthene-based starting materials were easily prepared from 1,8-bis(arylethynyl)naphthalenes 6. Both buckybowls 3 and 4 are fragments of C60 , whereas 5 is a unique subunit of C70 . The curved structures were identified by X-ray crystallography, and they are deep bowls. The maximum π-orbital axis vector (POAV) pyramidalization angle in both 3 and 4 is 12.8°. Such a high curvature is very rarely obtained. Buckybowls 5 are less curved than the others because they have a lower density of five-membered rings, analogous to the tube portion of C70 . Cyclopentaannulation increases the bowl depths of 3 and 4, but not the maximum POAV pyramidalization angle. Among the eight buckybowls studied herein, five form polar crystals. The bowl-to-bowl inversion dynamics of these buckybowls can be classified into two types; one has a planar transition structure, whereas the other has an S-shaped transition structure. A larger longitudinal length of these buckybowls corresponds to a stronger preference for the latter. The photophysical properties of these buckybowls were examined and compared with those of C60 and C70 . Buckybowls 5 have absorption bands at wavelengths greater than 450 nm, which are similar to those of C70 . The chiral resolution of the mono-substituted buckybowl 4 ac was also studied by using HPLC with a chiral column.

Bowl‐Shaped Fragments of C70 or Higher Fullerenes: Synthesis, Structural Analysis, and Inversion Dynamics

Super bowl: Fragments of C70 or higher fullerenes were easily prepared from 1,8-bis(arylethynyl)naphthalenes. The curved structures were identified by X-ray crystallography. These rigid bowl-shaped molecules have a deep bowl depth (approximately 2.30 Å) and their bowl inversions proceed via an S-shaped transition structure with a very high inversion barrier (approximately 80 kcal mol−1). Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Spur Gear Tooth Design with S-Shaped Transition Curve using T-Bézier Function

This article has been removed: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).Further to an investigation the International Conference on Advances Science and Contemporary Engineering 2012, Procedia Engineering, Volume 50, has been removed by the publisher due to insufficient assurances by the programme organisers that the professional ethical codes of publishing and standards were applied consistently.Where the copyright in individual papers was transferred to the publisher, these transfers are now considered null and void, and revert back to the authors.For author enquiries please contact: [email protected].

A new method in highway route design: joining circular arcs by a single C-Bézier curve with shape parameter

We constructed a single C-Bezier curve with a shape parameter for G2 joining two circular arcs. It was shown that an S-shaped transition curve, which is able to manage a broader scope about two circle radii than the Bezier curves, has no curvature extrema, while a C-shaped transition curve has a single curvature extremum. Regarding the two kinds of curves, specific algorithms were presented in detail, strict mathematical proofs were given, and the effectiveness of the method was shown by examples. This method has the following three advantages: (1) the pattern is unified; (2) the parameter able to adjust the shape of the transition curve is available; (3) the transition curve is only a single segment, and the algorithm can be formulated as a low order equation to be solved for its positive root. These advantages make the method simple and easy to implement.

Fair cubic transition between two circles with one circle inside or tangent to the other

This paper describes a method for joining two circles with a C-shaped and an S-shaped transition curve, composed of a cubic Bezier segment. As an extension of our previous work; we show that a single cubic curve can be used for blending or for a transition curve preserving G 2 continuity regardless of the distance of their centers and magnitudes of the radii which is an advantage. Our method with shape parameter provides freedom to modify the shape in a stable manner.

Transition between concentric or tangent circles with a single segment of [formula omitted] PH quintic curve

The paper describes a method to join two circles with a C-shaped and an S-shaped transition curve, composed of a Pythagorean hodograph quintic segment, preserving G 2 continuity. It is considered desirable to have such a curve in satellite path planning, highway or railway route designing, or non-holonomic robot path planning. As an extension of our previous work, we show that a single quintic curve can be used for blending or for a transition curve between two circles, including the previously unsolved cases of concentric and tangential circles.

S-Shaped Transition and Catapult Effects

Among today's rich economies, per capita output levels had diverged before converging to the levels of the frontier economy. Many non-rich countries also appear to follow this pattern of growth. Since frontier economies have grown at stable rates, non-frontier economies display an S-shape transition path. Along this transition, there are catapult effects: longer episodes of divergence are associated with faster subsequent rates of convergence to the frontier. We construct and quantitatively assess a model of S-shaped transition with catapult effects. Deviations in per capita output from frontier levels are endogenous, while conventional growth accounting would classify these as TFP differences.

S-shaped Transition and Catapult Effects

S-shaped Transition and Catapult Effects

Theory and Measurement of Modern Transition

The process of modernization is neither instantaneous nor homogeneous across countries. Given the large productivity growth gap between traditional and modern sectors, the gradual and varying degree of transition between these technologies seems puzzling. We develop a theory of transition that resolves this puzzle. The key forces are sector-specific complementarity between work-experience and labor, and exogenous technical progress present only in the modern sector. Using nationally representative micro data from the Socio-Economic Survey of Thailand (1976-1996), we measure the theory by estimating cross-sectional earnings functions, and assess if the model captures the observed dynamics of transition. The model jointly explains the gradual and S-shaped transition, stagnant growth of aggregate earnings, and the rise and fall of experience-earnings profiles in Thailand.

G 2 Planar Cubic Transition Between Two Circles

Meek and Walton [2] have examined the shapes of G 2 planar single cubic transition S- and C-shaped curves connecting two circles. We show that use of another parameter makes their analysis more complete and easier to read. We presented a very short algorithm with less restrictive ratio of the larger to the smaller radii of the given circular arcs. It is more comfortable for practical applications. Our compact algorithm also guarantee the absence of interior curvature extrema for an S-shaped transition curve and one curvature extrema for C-shaped transition curve. Transition curves of monotonically increasing or decreasing curvature between circles also play an important role in the design of highways and railways.