Practical Design Calculations Research Articles

Kinetic Regularities of the Filtration Drying of Barley Brewer’s Spent Grain

The paper describes the study of the kinetics of filtration drying of barley brewer’s spent grain. The dependencies of the process at different parameters of the stationary layer and the heating agent are presented: different heights of the wet material H (40 mm, 80 mm, 120 mm, and 160 mm), different temperatures of the heating agent T (50 °C, 70 °C, 80 °C, and 90 °C), and the velocities of the heating agent through the stationary layer of material v0 (1.26 m/s, 1.55 m/s, 1.81 m/s, 2.31 m/s, and 2.82 m/s). The kinetic regularities of two drying periods were determined: the period of complete saturation of the heating agent with moisture and the period of partial saturation of the heating agent with moisture. The calculation dependencies describing the intensity of the filtration drying process in both periods are proposed. The equations for determining the drying time of barley brewer’s spent grain τI and τII during both periods are proposed. The absolute value of the maximum relative error of the experimental values of moisture content from the theoretically calculated ones is 19.83 %, and the average value of the relative error is 3.15 %, which is acceptable for practical design calculations of drying equipment.

An efficient analysis of oblique reflection of airborne ultrasound beams from thin membranes for gas sensing.

The use of the angular spectrum method (ASM) to simulate the reflection of airborne ultrasound beams from a thin membrane separating air from a mixture of air and another gas is examined. The main advantage of this method is its high computing speed and efficiency for practical design calculations, suitable for sensing applications. The implemented ASM code is validated against custom Rayleigh integral code in a pure propagation simulation. In addition, ultrasound beam reflection calculations using ASM with finite element numerical results and experimental measurements are compared, finding good agreement in both cases. Then, ASM is used to estimate the sensitivity of specular reflection signals to variations in the composition of the incidence medium as a function of the angle of incidence. Conditions for which a reflection signal using inexpensive commercial ultrasound emitter/receiver at 40 kHz, in a simple configuration, offer a high enough sensitivity suitable for monitoring air quality indoors are found.

Calibrated Numerical Approach for the Dynamic Analysis of Glass Curtain Walls under Spheroconical Bag Impact

The structural design of glass curtain walls and facades is a challenging issue, considering that building envelopes can be subjected extreme design loads. Among others, the soft body impact (SBI) test protocol represents a key design step to protect the occupants. While in Europe the standardized protocol based on the pneumatic twin-tire (TT) impactor can be nowadays supported by Finite Element (FE) numerical simulations, cost-time consuming experimental procedures with the spheroconical bag (SB) impactor are still required for facade producers and manufacturers by several technical committees, for the impact assessment of novel systems. At the same time, validated numerical calibrations for SB are still missing in support of designers and manufacturers. In this paper, an enhanced numerical approach is proposed for curtain walls under SB, based on a coupled methodology inclusive of a computationally efficient two Degree of Freedom (2-DOF) and a more geometrically accurate Finite Element (FE) model. As shown, the SB impactor is characterized by stiffness and dissipation properties that hardly match with ideal rigid elastic assumptions, nor with the TT features. Based on a reliable set of experimental investigations and records, the proposed methodology acts on the time history of the imposed load, which is implicitly calibrated to account for the SB impactor features, once the facade features (flexibility and damping parameters) are known. The resulting calibration of the 2-DOF modelling parameters for the derivation of time histories of impact force is achieved with the support of experimental measurements and FE model of the examined facade. The potential and accuracy of the method is emphasized by the collected experimental and numerical comparisons. Successively, the same numerical approach is used to derive a series of iso-damage curves that could support practical design calculations.

The New Australian Concrete Structures Standard AS 3600:2018 – Aspects of its Complexity and Effectiveness

Australian Standard for Concrete Structures AS 3600-1988, the first of the AS 3600 series, was published in March 1988. Since then, AS 3600 has been revised four times and published consecutively at between six to nine-year intervals as AS 3600-1994, AS 3600-2001, AS 3600-2009 and the latest, AS 3600-2018. The changes incorporated in AS 3600-2018 concern mainly the following topics: 1. Stress-block configuration for bending analysis and design of reinforced and prestressed members 2. Shear and torsional strengths of reinforced and prestressed members 3. Values of the strength capacity reduction factor,  for different member strengths 4. Effective moment of inertia for deflection calculations As part of a review, a summary of the relevant new design procedures and associated formulas have been prepared. Research worldwide on the mechanics and strength of concrete structures – a rather mature discipline – is sustaining a state of diminishing return. Australia is no exception. In particular, the modifications identified above have led to more complicated processes which require increased computational efforts. Academically, such added complexity may be considered as a disciplinary upgrade. Concrete engineering practitioners, on the other hand, deserve to be advised of the effectiveness, or worthiness, of such an advance. In each of the concerned topics and for practical problems, analysis and design calculations have been carried out using the updated specifications given in AS 3600-2018, as well as those existing in the superseded AS 3600-2009. Based on the analysis results and design outcomes, observations are made in regard to the complexity and effectiveness of this Australia‟s premier concrete structures code.

In-plane elastic flexibility of cross laminated timber floor diaphragms

No appropriate method exists to calculate the in-plane flexibility of Cross Laminated Timber as a floor diaphragm. This flexibility affects the load distribution between shear walls, bracing or cores, as well as adding to local deflections and inter-storey drift. This paper presents a sensitivity analysis based on experimentally measured connection behaviour from the literature and the present study. An important new contributing factor is described: the connection of the floor panels to the supporting wall panels below allows the walls to act as top and bottom chords in the bending and shear of the panel. A new equivalent frame model is described to capture the significant mechanisms of deformation of the diaphragm, validated against a planar finite element model of the elastic behaviour of the panels and the connections between them. The low computational cost of the simplified model allows a wide sensitivity analysis to be carried out, and also makes it suitable for practical design calculations. The flexibility of the floors studied here was seen to be dominated by the slip between panels, rather than panel rotation or bending of the panels themselves. The supporting walls have a strong influence on the moment distribution, but do not strongly influence the slip between panels.

Practical Design Calculations for Groundwater and Soil RemediationPractical Design Calculations for Groundwater and Soil Remediation, second edition. KuoJeff. CRS Press/Balkema, Leiden, 2014, £82.00 (hardback) or £57.40 (e-book), 304 pp., ISBN: 978-1-4665-8523-2 (hardback) or 978-0-203-49099-0 (e-book)

new edition has updates throughout the text, and it presents all new material on air sparging, dual phase extraction, chemical oxidation, and vacuum pumps, as well as several new practical examples. It illustrates the engineering calculations needed during site assessment and remedial investigations. It also shows readers how to estimate the rates of groundwater movement and plume migration. This book provides important design calculations for vadose zone soil remediation as well as groundwater remediation--

Buckling of Buoyancy-Assisted Tubulars

Summary Use of buoyancy provides multiple solutions to overcome the drag problem for wells with shallow and high step-out profiles. Although both full- and partial-flotation methodologies have been used successfully to extend the reach in many field cases, the influence of buoyancy on tubular instability has not been investigated yet. This paper presents an extensive experimental and analytical study, focusing on static tubular instability inside horizontal wellbores with emphasis on buoyancy. In terms of the experimental research, running tubulars into horizontal wellbores was simulated with four different pipes, varying buoyancy, and varying loading speed. Throughout the tests, axial loads both applied to the pipe and transmitted through the pipe were recorded simultaneously, with respect to pipe displacement. Experiments reveal that currently existing models give reasonable approximations as long as buoyancy is not included in the tests. The major interpretation from the experiments is contrary to what currently existing expressions imply (i.e., tubular buckles immediately as effective weight approaches zero; even for naturally buoyant conditions, considerable amount of axial load is still required for both buckling initiation and helix formation). As buoyancy increases further, results and predictions diverge from each other considerably. To eliminate the discrepancies between results and predictions, theoretical study was conducted. Empirical correlations that also consider the influence of buoyancy on critical buckling loads are presented. Finally, another pipe was also tested within different buoyancy conditions to validate the equations developed. Experimental results of this pipe closely match the new analytical findings. This experimental and analytical study provides useful results for future applications with buoyancy-assisted tubulars, in terms of practical engineering and design calculations.

Extreme ocean waves. Part I. The practical application of fully nonlinear wave modelling

Abstract This paper concerns the description of large surface water waves in realistic ocean spectra and explains how fully nonlinear wave modelling can be applied in practical design calculations. In particular, the proposed methodology incorporates: (i) the transitory nature of individual waves or wave groups arising in a random or irregular sea involving a significant spread of wave energy across the frequency domain; (ii) the short-crestedness of waves arising due to the directionality of the underlying wave components; and (iii) the nonlinearity associated with the evolution of the largest waves. The procedures outlined build directly upon two advances in wave modelling, reported by Bateman et al. [1,2]. By combining these solutions with initial or starting conditions originating from statistical theory describing the most probable shape of a large linear wave, fully nonlinear descriptions of extreme waves in realistic sea states can be achieved. Furthermore, such calculations can be undertaken with relatively modest computational effort and are directly relevant to a wide range of design wave calculations.

A practical guide for optimal designs of experiments in the Monod model

The Monod model is a classical microbiological model often used in environmental sciences, for example to evaluate biodegradation processes. The model describes microbial growth kinetics in batch culture experiments using three parameters: the maximal specific growth rate, the saturation constant and the yield coefficient. However, identification of these parameter values from experimental data is a challenging problem. Recently, it was demonstrated theoretically that the application of optimal design theory in this model is an efficient method for both parameter value identification and economic use of experimental resources [Dette, H., Melas, V.B., Pepelyshev, A., Strigul, N., 2003. Efficient design of experiments in the Monod model. J. R. Stat. Soc. B 65 (Part 3), 725–742]. The purpose of this paper is to provide this method as a computational “tool” such that it can be used by practitioners without a strong mathematical and statistical background for the efficient design of experiments in the Monod model. The paper presents careful explanations of the principal theoretical concepts, and a simple algorithm for practical optimal design calculations.

The influence of non-equilibrium dissociation on the flow produced by shock impingement on a blunt body

We describe an investigation of the effects of non-equilibrium thermochemistry on the interaction between a weak oblique shock and the strong bow shock formed by a blunt body in hypersonic flow. This type of shock-on-shock interaction, also known as an Edney type IV interaction, causes locally intense enhancement of the surface heat transfer rate. A supersonic jet is formed by the nonlinear interaction that occurs between the two shock waves and elevated heat transfer rates and surface pressures are produced by the impingement of the supersonic jet on the body. The current paper is motivated by previous studies suggesting that real gas effects would significantly increase the severity of the phenomenon. Experiments are described in which a free-piston shock tunnel is used to produce shock interaction flows with significant gas dissociation. Surprisingly, the data that are obtained show no significant stagnation enthalpy dependence of the ratio of the peak heat transfer rates with and without shock interaction, in contrast to existing belief. The geometry investigated is the nominally two-dimensional flow about a cylinder with coplanar impinging shock wave. Holographic interferometry is used to visualize the flow field and to quantify increases in the stagnation density caused by shock interaction. Time-resolved heat transfer measurements are obtained from surface junction thermocouples about the model forebody. An improved model is developed to elucidate the finite-rate thermochemical processes occurring in the interaction region. It is shown that severe heat transfer intensification is a result of a jet shock structure that minimizes the entropy rise of the supersonic jet fluid whereas strong thermochemical effects are promoted by conditions that maximize the entropy rise (and hence temperature). This dichotomy underlies the smaller than anticipated influence of real gas effects on the heat transfer intensification. The model accurately predicts the measured heat transfer rates. Improved understanding of the influence of real gas effects on the shock interaction phenomenon reduces a significant element of risk in the design of hypersonic vehicles. The peak heat transfer rate for the Edney type IV interaction is shown to be well-correlated, in the weak impinging shock regime, by an expression of the form [equation] for use in practical design calculations.

Practical Design Calculations for Groundwater and Soil Remediation

Practical Design Calculations for Groundwater and Soil Remediation

A simple model for heat and mass transfer in absorption cooling systems (ACSs)

The article presents a simple technique for the purpose of heat and mass transfer analysis in an ACS. The LiBr/water ACS was selected as an example. Based on optimum operation conditions (i.e., the maximum cooling temperature delivered by the ACS), simple but effective expressions were derived in terms of the mass flow rate of absorbent-the most important parameter for practical design calculations. The results show that the proposed technique provides, for practical application purposes, a useful tool for a general analysis of the ACS as well as for the system design purpose.

Static and dynamic lateral deflexion of piles in non-homogeneous soil stratum

The Paper presents the results of a systematic parametric investigation of the static and dynamic response of single free-head piles embedded in a soil stratum, the modulus of which increases linearly with depth. The study is conducted by means of a dynamic finite-element formulation which accounts for the three-dimensionality of soil deformation while properly reproducing the radiation damping characteristics of the system. The soil is modelled as a linear hysteretic continuum and the excitation consists of a sinusoidally time-varying horizontal force or moment, applied at the pile head. Comprehensive plots of the results are presented in non-dimensional form, for a wide range of the most significant dimension-less groups of problem parameters. For the response of flexible piles, in particular, simple algebraic expressions are developed in terms of the ratio Ep/Es, of the pile and soil moduli. These expressions, being valid for several values of Poisson's ratios of the soil, compare favourably with results from previous studies and are expected to be useful in practical design calculations. Cet article donne les résultats de recherches paramétriques systématiques sur la réponse statique et dynamique des pieux libres en tête encastrés dans une couche de sol dont le module s'accroît linéairement avec la profondeur. L'étude est basée sur une formulation d'éléments finis dynamiques qui tient compte de la nature tridimensionelle de la déformation du sol, en même temps qu'elle reproduit de façon correcte les caractéristiques d'amortissement du systéme. Le sol est modehsé comme un continuum avec hystérśsise linéaire et l'excitation consiste en une force horizontale qui varie de façon sinusoidale dans le temps appliquée en tête du pieu. Les résultats sont tracés de maniére compréhensive sous une forme non-dimensionnelle pour une grande variété des groupes les plus importants des paramétres sans dimensions caractérisant le probléme. Plus particuliérement pour la réponse des pieux flexibles des expressions simples algébriques sont présentées en fonction du rapport Ep/Es des modules du pieu et du sol. Ces expressions, qui sont valables pour plusieurs valeurs du coefficient de Poisson pour le sol sont supérieures à celles fournies par les etudes précédentes, et on s'attend à ce qu'elles soient utiles pour els calculs pratiques des projects de fondations.

Otec cold water pipe design for problems caused by vortex-excited oscillations

Vortex-excited oscillations of marine structures result in reduced fatigue life, large hydrodynamic forces and induced stresses, and sometimes lead to structural damage and to destructive failures. The cold water pipe of an Ocean Thermal Energy Conversion (OTEC) plant is nominally a bluff, flexible cylinder with a large aspect ratio ( L/ D = length/diameter), and is likely to be susceptible to resonant vortex-excited oscillations. The objective of this paper is to survey recent results pertaining to the vortex-excited oscillations of structures in general and to consider the application of these findings to the design of the OTEC cold water pipe. Practical design calculations are given as examples throughout the various sections of the report. This paper is limited in scope to the problems of vortex shedding from bluff, flexible structures in steady currents and the resulting vortex-excited oscillations. The effects of flow non-uniformities, surface roughness of the cylinder, and inclination to the incident flow are considered in addition to the case of a smooth cylinder in a uniform stream. Emphasis is placed upon design procedures, hydrodynamic coefficients applicable in practice, and the specification of structural response parameters relevant to the OTEC cold water pipe. There are important problems associated with the shedding of vortices from cylinders in waves and from the combined action of waves and currents, but these complex fluid/structure interactions are not considered in this paper.

Propagation characteristics of parabolic-index fiber modes: linearly polarized approximation

The linearly polarized approximation (LPA) is employed for the analysis of the propagation characteristics of the guided modes in parabolic-index fibers. Characteristic equations for fibers in both the infinite- and finite-cladding configurations are derived and the conditions for the core-mode cutoffs are thereby deduced. In particular, it is shown that the effects of the finite cladding on the properties of the guided modes can be accounted for by a direct generalization of the LPA that has been used for the analysis of infinite-cladding fibers. Furthermore, it is demonstrated that the LPA is applicable even when the cladding layer is thin compared with the core radius and the refractive index of the surrounding medium is much smaller than that of the cladding, provided the weakly guiding condition for the core modes is fulfilled and the propagating radiation frequency is far from the cladding-mode cutoff. The good agreement between the results obtained by the LPA and those calculated by the vector wave analysis, which is overwhelmingly complex for the finite-cladding fibers, demonstrates the appeal of the LPA by providing simple and yet sufficiently accurate formulas for the practical design calculations for parabolic-index fibers. It is also pointed out that the mathematical procedure employed in this paper can be adapted for other types of graded-index fibers.

The Calculation of Illumination in Practical Lighting Design

Practical design calculations must be simple and high accuracy is rarely required. The widely used lumen-method is becoming increasingly dependable; local lighting methods are nevertheless indispensable. The applicability of the point source concept is discussed, and the principles of line source calculations using the sector flux concept are briefly given. An example shows the combined use of point and line source methods. Flux relations are summarized.

Discussion at Winter convention: The synchronous converter theory and calculations

E. B. Shand: From the standpoint of practical design calculations, I believe that the formulas in the complex forms given are not generally applicable, due to the fact that the accuracy of design calculations is limited by a number of factors not considered in the paper. An instance of this may be found in equation (20) for voltage ratio. This expression may be simplified very greatly by introducing coefficients obtained directly from the converter field form without going through the process of actual harmonic analysis, which have a greater degree of accuracy than those of the calculated field form.