bluuebunny/crossref_metadata_2025 huggingface dataset:
Recognition of distorted QR codes with one missing position detection pattern
Authors: Huang Jianfen , Li Liyan , Wang Xiao , Lu Baoli , Liu Yuliang
Published: October 2020

Quick response (QR) codes are widely used in many fields. Various QR code recognition approaches have been proposed to improve the accuracy of decoding QR code. However, the recognition of distorted QR codes with one missing position detection pattern (PDP) remains a problem. In this study, based on the vector relationship and the structural features, the authors introduce a new method for decoding distorted QR code with one missing PDP. Three methods, Zxing, Halcon, and the newly proposed method, are used to test the decoding capability. For QR codes with one missing PDP, the experimental results show that the proposed method could meet the recognition angle range as much as 110°, while Zxing fails to recognise, and the angle of decoding for Halcon is 90°. Especially, the proposed method is available at an extremely harsh luminance and contrast environment, e.g. both phases as a 60% discount, when the decoding angle of Halcon is only 35°, while the proposed one better than 2.7 times of it. Besides, the proposed method is more robust to decode the QR codes with a missing PDP under different backgrounds and noisy images.
Energy shaping controller design of three‐phase quasi‐Z‐source inverter for grid‐tie
Authors: Ma Dazhong , Cai Zhiyang , Wang Rui , Sun Qiuye , Wang Peng
Published: October 2020

Although the control strategy regarding quasi‐Z‐source inverter (qZSI) has been widely studied, the dynamic response and steady‐state accuracy of the system with a non‐linear section should be further improved. Based on this, this study proposes an energy shaping control (ESC) method based on the port‐controlled Hamiltonian (PCH) model for qZSIs. Firstly, based on the average state‐space model, the PCH model of the qZSI system is first built, which is an indispensable preprocessing for the following controller design. Based on the proposed model, the ESC method combining the interconnect matrix with damping configuration is proposed to improve the dynamic response and steady‐state accuracy, which is verified through comparing with several existing linear and non‐linear control strategies in detail. Finally, simulation and experimental results verify the effectiveness of the proposed method.
Ophthalmology Applicant Perceptions of Two Residency Application Services: The San Francisco Match Central Application Service and Electronic Residency Application Service
Authors: Dharssi Shazia , Woreta Fasika A. , Boland Michael V.
Published: October 2020

Purpose Given ophthalmology residency programs are transitioning to include the internship year, either through “joint” or “integrated” 4-year programs, we set out to identify applicant preferences regarding the match and their experiences with two residency application systems: (1) the Central Application Service (CAS) and (2) the Electronic Residency Application Service (ERAS).

Design This study is designed as a retrospective repeated cross-sectional survey.

Methods A 15-question online survey was sent to 196 and 461 applicants to the 2019 and 2020 ophthalmology match cycles, respectively. Questions from the survey assessed user experiences with specific components of both application services and evaluated preferences regarding the future of the ophthalmology match.

Results Responses were received from 208 (32%) applicants. A majority of users had positive experiences with both application services; for CAS, 162 (78%) applicants had a positive experience, compared with 111 (53%) for ERAS. When compared directly, applicants favored the CAS (60%) to ERAS (21%). Furthermore, 108 (52%) respondents stated that they would prefer ophthalmology continue to use both the CAS and ERAS, while 47 (23%) respondents indicated a desire for the CAS to become the only application system for both matches.

Conclusion Although half of all respondents prefer that both the CAS and ERAS systems are utilized for the match process, many express a desire for a single matching program. As ophthalmology residency programs move to joint and integrated 4-year programs, the complexity of matching will increase. Further evaluation of applicant preferences during this transition phase is needed as applicants are required to apply to a variety of different joint and integrated internship and ophthalmology programs.
Hydroxylated sphingolipid biosynthesis regulates photoreceptor apical domain morphogenesis
Authors: Hebbar Sarita , Schuhmann Kai , Shevchenko Andrej , Knust Elisabeth
Published: October 2020

Apical domains of epithelial cells often undergo dramatic changes during morphogenesis to form specialized structures, such as microvilli. Here, we addressed the role of lipids during morphogenesis of the rhabdomere, the microvilli-based photosensitive organelle of Drosophila photoreceptor cells. Shotgun lipidomics analysis performed on mutant alleles of the polarity regulator crumbs, exhibiting varying rhabdomeric growth defects, revealed a correlation between increased abundance of hydroxylated sphingolipids and abnormal rhabdomeric growth. This could be attributed to an up-regulation of fatty acid hydroxylase transcription. Indeed, direct genetic perturbation of the hydroxylated sphingolipid metabolism modulated rhabdomere growth in a crumbs mutant background. One of the pathways targeted by sphingolipid metabolism turned out to be the secretory route of newly synthesized Rhodopsin, a major rhabdomeric protein. In particular, altered biosynthesis of hydroxylated sphingolipids impaired apical trafficking via Rab11, and thus apical membrane growth. The intersection of lipid metabolic pathways with apical domain growth provides a new facet to our understanding of apical growth during morphogenesis.
Classification of various sources of error in range assessment using proton radiography and neural networks in head and neck cancer patients
Authors: Oria Carmen Seller , Marmitt Gabriel Guterres , Both Stefan , Langendijk Johannes A , Knopf Antje C , Meijers Arturs
Published: October 2020

This study evaluates the suitability of convolutional neural networks (CNNs) to automatically process proton radiography (PR)-based images. CNNs are used to classify PR images impaired by several sources of error affecting the proton range, more precisely setup and calibration curve errors. PR simulations were performed in 40 head and neck cancer patients, at three different anatomical locations (fields A, B and C, centered for head and neck, neck and base of skull coverage). Field sizes were 26 × 26cm2 for field A and 4.5 × 4.5cm2 for fields B and C. Range shift maps were obtained by comparing an unperturbed reference PR against a PR where one or more sources of error affected the proton range. CT calibration curve errors in soft, bone and fat tissues and setup errors in the anterior–posterior and inferior–superior directions were simulated individually and in combination. A CNN was trained for each type of PR field, leading to three CNNs trained with a mixture of range shift maps arising from one or more sources of range error. To test the full/partial/wrong agreement between predicted and actual sources of range error in the range shift maps, exact, partial and wrong match percentages were computed for an independent test dataset containing range shift maps arising from isolated or combined errors, retrospectively. The CNN corresponding to field A showed superior capability to detect isolated and combined errors, with exact matches of 92% and 71% respectively. Field B showed exact matches of 80% and 54%, and field C resulted in exact matches of 77% and 41%. The suitability of CNNs to classify PR-based images containing different sources of error affecting the proton range was demonstrated. This procedure enables the detection of setup and calibration curve errors when they appear individually or in combination, providing valuable information for the interpretation of PR images.
Computer modeling of the acoustic path of a normal probe in cast iron with globular graphite
Authors: Danilov V N , Voronkova L V
Published: October 2020

Using the previously developed model for estimating the attenuation coefficient of elastic longitudinal waves in cast iron due to their Rayleigh scattering on graphite inclusions, we studied the influence of such attenuation for cast iron with spherical graphite on the characteristics of signals with frequency spectra of different widths depending on the cast iron models and the distance traveled by the ultrasonic wave.
Development of an automated system for ultrasonic testing of products obtained by additive manufacturing processes
Authors: Gordeeva L F , Prokhorovich V E , Bychenok V A , Alifanova I E
Published: October 2020

The authors conduct research on ultrasonic testing of products obtained by additive manufacturing processes. This article provides a diagram and a general view of the model of the developed ultrasonic system. The article contains a description of the object under study with simulated defects, as well as a scheme for its testing. As the results of the study, the article provides A-scans.
Eddy current method for steel billet mould level control
Authors: Terekhin I V , Chernova E A
Published: October 2020

The relevant issue of metal level control in a mould of continuous casting machine (CCM) is improving the measurement accuracy when adding slag powders in a mould. The main disadvantage of the widely used radiometric metal level control devices (MLCDs) is the dependence of the output signal on the amount of slag in a mould. Eddy current (EC) sensor for metal level control is not sensitive to the slag. It detects metal level indirectly by temperature of copper mould wall, which is in contact with liquid metal. As a consequence, eddy current MLCD speed of response is limited to the time constant of thermal transient processes in a mould wall, which is insufficient to modern steel industry. This paper deals with a mould CCM metal level control method by means of the EC sensor based on signal detection from the liquid metal through a copper mould wall. The direct method provides required signal speed of response of eddy current MLCD in the case of steel casting with the slag.
Design of multiprobe for fuel-elements cladding eddy current testing
Authors: Krukov A S , Shchukis E G , Kodak N P , Lunin V P
Published: October 2020

This article presents a study of the eddy current flaw detector (ECFD) numeric model in order to choose the necessary parameters for zirconium pipes control. As a result of mathematical modeling, the multiprobe ECFD was designed and the eddy flaw control conditions were found. The analysis of defect signals with various geometrical parameters leads to a conclusion that the presence of discontinuity registration needs a phase method of data processing.
Identification of defect type in non-destructive testing of polymer composite structures
Authors: Kuryatin A , Rusakov D , Chernushin V
Published: October 2020

The paper describes non-destructive testing of composite honeycomb materials, to identify the type of defect, such as delamination, non-adhesion, inclusion, etc. Practical recommendations on testing monolithic, combined, multilayer and reinforced structures and defect identification have been given.
Development of measurement science in the context of the fourth industrial revolution
Authors: Taymanov R , Sapozhnikova K
Published: October 2020

The fourth industrial revolution is characterised by the wide introduction of cyber-physical systems, robotics and the Internet of Things. The efficiency of smart cities, smart manufacturing, smart transport, etc. can be provided only if the measurement information coming from sensors is trustworthy. In each facility, the number of sensors can vary from thousands to tens of thousands. The avalanche-like growth in the number of measuring instruments should be accompanied by quite frequent check of their metrological serviceability. In this case, a significant reduction in maintenance labour costs can be achieved by increasing calibration or verification intervals by many times. The development in this direction is challenging because of the growing demand for the increase in the number of complex properties that should be quantitatively estimated. The fundamentals of metrological check and features of applying object digital twins for debugging multichannel measuring systems have been given. The need for international standards in this field has been emphasised.
Thermography of inner surfaces of high-temperature industrial facilities
Authors: Bykov A A , Khokhlov D D , Gorevoy A V , Volkov M V
Published: October 2020

Thermography of inner surfaces of high-temperature facilities is an important task of industrial non-destructive testing. Existing methods operating in the visible wavelength range require the spectral scanning during the image acquisition to determine the distribution of temperature across the field of view. The infrared imaging techniques require specific lenses and image sensors. In this paper, we propose a method for remote determination of the spatial temperature distribution that is not limited by the mentioned restrictions. It is based on the use of an image sensor with a mosaic spectral filter array installed on it. This paper presents the layout of the prototype and the possibility of its practical application demonstrated in laboratory conditions.
A method of synthesis of small-sized high-speed optical measuring flaw detection systems
Authors: Chichigin B A , Groo I A
Published: October 2020

A method for the synthesis of small-sized high-speed measuring flaw detection systems has been developed, with which it is possible to develop and create systems to solve said problem. For testing of this method, a prototype of the system was developed. Principles of developing of the prototype, its software operation and the results of its testing are provided in this article.
Dependence of the characteristics of acousto-optic modulators and filters based on single-crystal media on the radiation wavelength in the infrared and terahertz ranges
Authors: Nikitin P A , Polikarpova N V
Published: October 2020

A theoretical study of the dependence of the spectral resolution of acousto-optic filters and the maximum number of resolved elements of acousto-optic deflectors on the radiation wavelength in the range 40 − 100 μm was carried out. Semiconductor single crystals with a cubic crystal lattice, which are transparent in the considered range, were chosen as the material of acousto-optic devices. It is shown that with increasing wavelength from 40 to 100 μm, the spectral resolution of the filters increases from 10 to 103, and the maximum number of resolved elements of the deflectors decreases from 104 to 102.
Can the ghost imaging increase the lateral resolution of surface plasmon resonance microscopy?
Authors: Khasanov I Sh , Zykova L A
Published: October 2020

Surface plasmon resonance (SPR) microscopy is one of the most sensitive optical label-free methods of microscopy. Nevertheless, it does not have a sufficiently high lateral resolution in comparison with other methods of optical microscopy. By analogy with the scattering medium, surface plasmon polaritons (SPPs) blur the observed area. To eliminate this disadvantage, we propose to adapt the method known as ghost imaging (GI), which is notable for its tolerance to environmental aberrations between an object and a camera. In this article, we propose a ghost imaging scheme for a surface plasmon resonance microscope using a pseudo-thermal radiation source. We make a fundamental analysis of the factors affecting the resolution capability of the ghost SPR microscopy. We claim that applying the ghost imaging method to SPR microscopy can improve its lateral resolution by eliminating uncorrelated with modulated radiation phase noise generated by the process of random re-emission of surface electromagnetic wave (SEW) from the site of excitation. In combination of factors, the ghost imaging method of SPR microscopy is potentially capable of becoming outstanding among other methods of microscopy of thin films.
Denning phenology and reproductive success of wolves in response to climate signals
Authors: Mahoney Peter J , Joly Kyle , Borg Bridget L , Sorum Mathew S , Rinaldi Todd A , Saalfeld David , Golden Howard , Latham A David M , Kelly Allicia P , Mangipane Buck , Koizumi Catherine Lambert , Neufeld Layla , Hebblewhite Mark , Boelman Natalie T , Prugh Laura R
Published: October 2020

Arctic and boreal ecosystems are experiencing rapid changes in temperature and precipitation regimes. Subsequent shifts in seasonality can lead to a mismatch between the timing of resource availability and species’ life-history events, known as phenological or trophic mismatch. Although mismatch has been shown to negatively affect some northern animal populations, longer-term impacts across large regions remain unknown. In addition, animals may rely on climate cues during preceding seasons to time key life history events such as reproduction, but the reliability of these cues as indicators of subsequent resource availability has not been examined. We used remote sensing and gridded spatial data to evaluate the effect of climate factors on the reproductive phenology and success of a wide-ranging carnivore, the gray wolf (Canis lupus). We used global positioning system (GPS) location data from 388 wolves to estimate den initiation dates (n = 227 dens within 106 packs) and reproductive success in eight populations across northwestern North America from 2000 to 2017. Spring onset shifted 14.2 d earlier, on average, during the 18-year period, but the regional mean date of denning did not change. Preceding winter temperature was the strongest climatic predictor of denning phenology, with higher temperatures advancing the timing of denning. Winter temperature was also one the strongest and most reliable indicators of the timing of spring onset. Reproductive success was not affected by timing of denning or synchrony with spring onset, but improved during cooler summers and following relatively dry autumns. Our findings highlight a disconnect between climate factors that affect phenology and those that affect demography, suggesting that carnivores may be resilient to shifts in seasonality and yet sensitive to weather conditions affecting their prey at both local and regional scales. These insights regarding the relationship between climate and carnivore demography should improve predictions of climate warming effects on the highest trophic levels.
A Review on Use of Crushed Brick Powder as a Supplementary Cementitious Material
Authors: Mohan Mani , Apurva Aditya , Kumar Nishant , Ojha Abhishek
Published: October 2020

In India, it is estimated that 250 billion bricks are produced annually in about 100,000 kilns present all over the country. Mainly due to inefficient production processes, most of the blocks manufactured are of inferior quality, which ultimately becomes a significant source of waste production. The characteristics of Construction and Demolition wastes (C&D) are difficult to predict, but a considerable component of this type of solid waste comprises of bricks in masonry work. As more and more civil structures are nearing the end of their expected lifespan, proper management and disposal of C&D wastes are necessary to obtain a sustainable environment. Ground waste clay brick is a prospective pozzolanic material due to dehydroxylation of clay minerals during its manufacturing process at temperatures between 450°C and 700°C, leading to the disintegration of crystalline phases and formation of reactive anhydrous amorphous phases. A review of the existing literature regarding the use of crushed brick powder (CBP) from waste bricks as well as demolition debris as a supplementary cementitious material has been conducted. It has been observed that the pozzolanic character of clay used for making brick comes from calcining it at an optimum temperature, which is different for different clays. Cement replacement by CBP in concrete mostly causes increased compressive, flexural, and split – tensile strength at 28 and 90 days, indicating good pozzolanic behaviour. 10 – 25% replacement by CBP gives acceptable values of Strength Activity Index (SAI) at 7 and 28 days. Pore refinement causing the formation of additional hydration products due to pozzolanic reaction as well as filler effect of CBP are the primary factors causing improved durability of concrete. Limited research has been done on the effect of the chemical composition of raw clay on the pozzolanic potential of CBP. Future scope in this area can be on enhancement of pozzolanicity in CBP, the study of high volume replacement of CBP in concrete, and the effect of CBP replacement on corrosion of rebar.
A Study on Tensile Properties of Bamboo Textile Reinforced Composites
Authors: Jazeel I S , Remanan Mini
Published: October 2020

A composite material is a material, which combines complementary nature and features of two or more constituents to result in a new material with unique and outstanding characteristics when compared with its original constituents. Conventional fibres such as glass and carbon can be replaced by environment-friendly bamboo fibres having good mechanical properties. Also being fastest-growing plants in the world (growing at a rate of 3 cm per hour), bamboo is abundantly available. Better fibre-matrix interaction will result in good interfacial adhesion between fibre and matrix and thereby reduces voids in the composite. This paper describes the tensile properties of bamboo textile reinforced composites. In this study, two different types of bamboo textiles i.e. knitted and weaved are used. Hand layup technique was incorporated in the production of composites and after that, air-cooling is adopted. All the tensile testing specimens are prepared according to ASTM D3039. Variation of the tensile properties of composite with different layers of bamboo textile and age are studied. The number of layers varies from 1 to 10. Tensile properties of these two bidirectional bamboo textile reinforced composites are tested for 7 days and 28 days. Keeping, the fibre volume fraction constant, increasing the number of layers enhances the ultimate tensile strength. Further increase in the number of layers shows no considerable variation in its ultimate tensile strength. Modulus of elasticity and percentage elongation of bamboo textile reinforced composites are also investigated.
Sustainability of Construction with Textile Reinforced Concrete- A State of the Art
Authors: Alexander Anjana Elsa , Shashikala A P
Published: October 2020

Steel reinforcement in reinforced concrete structure is prone to corrosion. It has been found that a sustainable building material that can be used to replace steel from the construction industry is textile reinforcement. Textiles of high strength and fine-grained mortar are used to make a composite material termed as Textile Reinforced Concrete (TRC). This review paper presents an evaluation of different textiles that can be used as reinforcement in TRC, their bonding behaviour, durability characteristics and applications. A comprehensive overview on TRC reveals that TRC has excellent mechanical properties and durability characteristics. TRC is applicable for constructing lightweight, thin structural elements and for strengthening or repair of damaged structural elements.
Biochar Amended Concrete for Carbon Sequestration
Authors: Nair Jyothi J , Shika S , Sreedharan Vandana
Published: October 2020

With the rapid increase in built-up areas around the world, and the emergence of new cities, there is a potential of sequestering carbon in civil infrastructures. Biochar is the by-product of the pyrolysis of biomass, which can be introduced to the cement mortar and the cement concrete, as a replacement of cement as well as an additive. Biochar is effective in the carbon sequestration activity and results in the high internal curing action due to the high-water absorptive capacity. As the percentage of biochar increases the amount of carbon dioxide adsorbed is also observed to increase. However, it is imperative that biochar addition should not compromise the strength characteristics of concrete. As a well-accepted fact, the pozzolanic activity plays large importance on the durability and the strength gain of concrete. The present study is aimed at investigating the pozzolanic activity of the biochar. Biochar specimens were subjected to different pre-treatments, and the corresponding changes in the pozzolanic activity were studied. The biomass used for the study was locally available coconut shells and the pre-treatment was done with the 0.1N HCl. The pozzolanic activity was checked by calculating the amount of Ca(OH)2 fixation during the titration. It was observed that treatments at higher temperatures have no significant effect on the pozzolanic activity. And this suggests that pre-treatment of biochar at room temperature is enough for enhanced pozzolanic activity. The study has reaffirmed the potential use of biochar in making sustainable concrete fit for carbon sequestration.
Feasible use of Recycled Foam Concrete in Cement Mortar
Authors: Lalrinmawii Evangeline , Sahu Santosini , Sarkar Pradip , Davis Robin
Published: October 2020

Lightweight foam concrete blocks have gained popularity over the last decade, particularly in the construction of interior infill walls. Consequently, the construction and demolition waste generated by such foam concrete blocks are increasing regularly. Recycling of these wastes and using them in cement mortar or concrete as partial replacement of conventional material can be an essential step towards the management of construction and demolition waste as well as conservation of natural resources leading to sustainability. The present study aims to assess the feasibility of recycled Autoclaved Aerated Concrete (AAC) and Cellular Lightweight Concrete (CLC) blocks as a possible replacement of sand and cement in the manufacturing of mortar. This study investigates various physical and mechanical properties of mortar in which sand and cement are partially replaced with material from recycled AAC and CLC block. Chemical analysis of demolished AAC and CLC block samples determined using X-Ray Fluorescence (XRF) analysis to find out the differences in composition between the conventional materials and replaced material. This study concludes that materials from recycled AAC and CLC block can be used in cement mortar as partial replacement of either cement or sand up to 15-20% without significant reduction of strength.
Analysis of Slab Culvert Bridges using Conventional Method and Grillage Method
Authors: Pandey Amit Kumar , Nagarajan Praveen
Published: October 2020

IRC 112:2011, the Indian standard pertaining to concrete bridge design is based on the limit state design principle. It suggests the use of effective width method for the analysis of the structure. For many years, the analysis part of concrete bridge structures design has been based on two-dimensional (2D) analysis and the results obtained from longitudinal analysis were supposed to be valid over the whole bridge width. In this paper, the grillage method has been used to model and analyse the super-structure to get the three-dimensional effect, and a comparison of results between effective width method and grillage method is presented.
Bayesian Approach of Model Updating of Structural Parameters with Simulated Modal Data
Authors: Sengupta Partha , Chakraborty Subrata
Published: October 2020

The present study investigates the effectiveness of Bayesian approach of model updating of structure, using simulated modal data sets as evidence. The importance of the prediction of error implemented in the proposed Bayesian framework to assess its capability in sampling posterior values with improved accuracy has been highlighted. The natural frequencies and mode shapes of the structure are taken only as the evidence. The study highlighted the importance of the likelihood functions corresponding to the prediction of error between the experimental and predicted data. The study also implemented the likelihood functions corresponding to the prediction of error variances of natural frequencies only in sampling posterior values with higher accuracy. The efficacy of the proposed approach in dealing with the issue of incomplete data sets, that makes the problem typically ill-conditioned, is duly addressed. The present work also implemented model reduction technique to synthesise the mode shape ordinates at unmeasured degrees of freedom (DOF) from the reduced-order model. In addition, the efficiency of the proposed model reduction algorithm is explored by adding noises of varying percentages to the measured mode shape values. The proposed methodology is illustrated numerically to update the stiffness parameters of an eight-storey shear building model, considering simulated datasets contaminated by Gaussian error as evidence. Results with both incomplete and complete data sets using the proposed Markov Chain Monte Carlo approach are studied. The accuracy on the synthesis of mode shapes from unmeasured DOF using model reduction algorithm is also studied.
Computational and Experimental Modal Analysis of a Three Storied Building Model
Authors: Thasneem M Murshida , Thankachan Prince , Madhavan Pillai T M
Published: October 2020

Vibration-based health monitoring assists in determining the modal parameters and damage identification of a structure. This paper presents the computational and experimental modal analysis of a single bay three-storied building with steel slabs and aluminium columns. Three-dimensional finite element (FE) model of the structure is analysed using ABAQUS, and natural frequencies in the first three translational modes are determined. These results are compared with those obtained from field impact testing. A small variation in analytical and experimental results may be due to the simplified assumptions in FEA, physical and numerical uncertainties.
Finite Element Modelling of Confined Masonry Wall under In-plane Cyclic Load
Authors: Borah Bonisha , Kaushik Hemant B , Singhal Vaibhav
Published: October 2020

Confined masonry (CM) is an effective building construction technology for low-tech construction in seismic-prone regions. This paper focuses on developing a numerical model to study the in-plane seismic behaviour of CM wall. A half-scaled CM wall specimen is designed based on Mexican practice and tested under a combination of vertical load and in-plane cyclic load up to failure. Based on that a three dimensional (3D) finite element macro-modelling technique is developed using the commercial software package ABAQUS, where the masonry panel, RC tie-frame, and reinforcements are discretely modelled. The strength and stiffness degradation of masonry and concrete is defined using Concrete Damaged Plasticity (CDP), which is a damaged plasticity-based continuum constitutive model. All the input data in the numerical model are based on experimental test results and data obtained from past literature or inverse fitting, with justification. From the analysis, it is observed that the numerical results are in good agreement with the experimental. Therefore, the proposed model can be successfully practiced to model confined masonry walls.
Influence of Fibre Geometry on the Fracture of Steel Fibre Reinforced Concrete
Authors: Murugan Komathi , Stephen Stefie J , Gettu Ravindra
Published: October 2020

Steel fibre reinforced concrete (SFRC) is used in various structural applications such as slabs, pavements, hydraulic structures, tunnel linings etc., due to their ability to limit the initiation and propagation of cracks, thereby improving the tensile load-carrying capacity and toughness. Two important parameters affecting the mechanical performance of a given SFRC are the type and dosage of fibres. The study presented in this paper examines the influence of fibre geometry on the fracture properties, considering two different types of cold-drawn hooked-ended steel fibres. Details of the pertaining experimental investigations conducted on SFRC with two different hooked-end geometries (denoted as 3D and 5D) at equivalent dosages are included; the tests conformed to EN 14651:2005+A1:2007. With the change in geometry, from the more conventional (3D) hooked-end with one kink, to that with three kinks at the ends (5D), even with a reduction of dosage from 45 to 35 kg/m3, 5D fibres were found to exhibit a slight superior performance than 3D fibres.
A Review on Fatigue Life Prediction of Plain Concrete
Authors: Renju D R , Keerthy M S
Published: October 2020

Fatigue analysis of concrete structures is important since it is the limiting factor to service life of many infrastructures. The heterogeneity in concrete and its complex behaviour upon repetitive loading makes the fatigue life prediction of concrete erratic. This paper presents a review on the fatigue life prediction models of plain concrete. Review includes the deterministic and probabilistic approach for the prediction of fatigue life of concrete. It has been observed that deterministic approach depends on certain parameters and initial conditions and is not reliable for the prediction of fatigue life of concrete. So there is a demand for a more generalised model based on probabilistic approach which includes randomness in the fatigue failure of concrete. Recent studies show utilisation of artificial neural network, a computational tool based on this approach can be utilised to predict the fatigue behaviour of concrete.
A Study on Effect of Fluid on the Modal Characteristics of Ground Supported Water Tanks
Authors: Anagha B V , Nimisha P , Jayalekshmi B R
Published: October 2020

Liquid storage tanks are one of the essential lifeline structures which should function even after natural disasters. Water tanks in particular are essential for proper supply of water in the affected areas and for fire-fighting purposes. Sloshing is an important phenomenon occurring in partially filled tank with free surface. It can cause violent liquid motions that can cause instability in carrier-vessel and structural damage in the tank walls. To maintain the structural integrity of the carrier vessels, modal characteristics should be known as the impact of sloshing will increase when the excitation frequency matches with the natural frequency of container and result in resonant condition. This study investigates the modal characteristics such as natural frequency, mode shapes of square tank by 3-D finite element method using ANSYS 2019 R1software. The effect of impulsive and convective frequency of tanks with different fill levels and different boundary conditions are considered.
Performance of Alkali-Activated Aerated Concrete using Class C Fly Ash
Authors: Muthu Kumar E
Published: October 2020

This paper focuses on the factors influencing the properties of alkali-activated aerated paste and mortar with high calcium fly ash as the source material, by comparing oven and ambient curing conditions. Design of experiments with response surface methodology is used to study the influence of each of the parameters on the properties of alkali-activated paste and mortar. To achieve a stable pore formation with aeration cooled liquid alkaline solution with a temperature below 15°C is used. The influence of each of the factor and their interaction effects on properties such as density, compressive strength and absorption of water were studied. For a constant dry density, the compressive strength achieved by ambient curing is higher compared to oven curing i.e. for a density of 900 kg/m3 the compressive strength with ambient curing is 4.5MPa while for oven curing it is 2.75MPa. But less water absorption is observed for oven curing compared to ambient curing. While the water absorption achieved was lower for oven curing it was higher for ambient curing resulting in not less than 10%.
Application of Conditional Mean Spectrum in the Seismic Assessment of a Braced Frame Steel Structure
Authors: Jayarajan P
Published: October 2020

Detailed engineering of critical infrastructure and tall buildings require that their response be estimated from nonlinear response history analysis (NLRHA) by subjecting the structure to suites of earthquake accelerograms. Selection of ground motion records due to future earthquake events represents an important step in the robust assessment of structural response. As per the current practice, both site-specific uniform hazard spectrum (UHS) and conditional mean spectrum (CMS) are employed as the target spectra for ground motion record selection. The CMS approach is superior considering that it represents realistic seismic events and also consider the multiple natural periods of the structure. The paper presents the application of conditional mean spectrum in the seismic assessment of an eight-story ordinary braced steel structure built on an example site. The NLRHA was conducted using the ground motions spectrally matched to the CMS at different conditioning periods. It was found that the CMS spectrally matched to larger modal period always result in larger seismic demands. A comparison was also made between seismic demands obtained from UHS & CMS indicating that the structural response parameters are almost the same in both cases except the story shears & drifts which is dominated by UHS in lower floors and by CMS in upper floors.
A Review on Ambient Cured Geopolymer Concrete-Sustainable Concrete for the Future
Authors: Nithin A V , Soman Mini , Raj S Deepa
Published: October 2020

The cement industry is one of the major contributors to global warming due to the release of greenhouse gases. An alternative low emission binding agent is needed to reduce the environmental impact caused by cement production. Geopolymer binder is an ideal material to substitute cement binder. Geopolymer Concrete (GPC) is formed by the polymerisation of aluminates and silicates formed by the reaction of solid aluminosilicates with alkali activators. The source materials studied were waste by-products from industries. This paper reviews the strength and durability characteristics of Geopolymer Concrete under ambient curing conditions. The comparison and study of the morphology of different aluminosilicate source materials through X-ray diffraction (XRD) pattern and Scanning electron microscopy (SEM) analysis under different curing temperatures and the study on the chemical composition and its effect on alkali activators and aggregates helped to understand the nature and type of source materials and activators most desirable to develop GPC in ambient conditions. GPC formed in ambient curing conditions have considerable strength and durability characteristics and can be adopted as a sustainable replacement for conventional concrete.
Drift Response Evaluation of Buckling-Restrained Braced Frames (BRBFs) under Sequential Seismic Disturbances
Authors: Pandikkadavath Muhamed Safeer , Mangalathu Sujith , Oinam Romanbabu M , Ashwin Kumar P C , Sahoo Dipti Ranjan , Anoop Krishnan N M
Published: October 2020

Buckling Restrained Braced Frames (BRBFs) are reliable lateral load resisting systems featured with Buckling Restrained Braces (BRBs) to safeguard building frames against earthquake-induced damages. BRBs are axial yielding type metallic dampers characterised with stable and balanced hysteretic behavior along with excellent low-cycle fatigue capacity. However, BRBFs are susceptible to relatively large drift responses mainly due to low axial stiffness of BRBs resulted from the higher seismic response modification factor,R. In the event of sequential seismic actions immediately after mainshock may induce additional drift demands which may adversely affect the reusability and retrofitting or in the worst case, it may lead to premature collapse of the BRBFs. The present study encompasses on drift response demand evaluation of BRBFs under the combined action of the main shock and sequential secondary ground shocks. For the study, a medium-rise BRBF used in the past investigation is selected and re-designed as per the recommended prevailing seismic provisions. Nonlinear time history analysis of BRBFs under the action of a suit of sequential ground disturbances is carried out and the results are analysed in terms of drift responses.
Probabilistic Assessment of Torsional Buildings
Authors: Karuthedath Philip Luke , Davis Robin , Sarkar Pradip
Published: October 2020

Asymmetry/irregularity is an undesired building characteristic that nevertheless exists commonly due to modern-day structural definitions. Asymmetry in plan, due to the uneven distribution of mass or stiffness can cause torsional coupling under seismic loads. A well-defined parameter that can sufficiently represent the damage of torsional buildings is non-existent, which may be why probabilistic seismic assessment methods such as fragility analyses have not been done for such buildings. The present study proposes ‘Resultant Drift’ as a parameter that can define the failure behaviour of asymmetric buildings and utilises the 2000 SAC FEMA method to analyse the seismic risk and develop fragility curves. The study observes the dependency of the extent of asymmetry and storey height on the failure probability. Investigations on the maximum storey rotation for the selected parameters show the necessity of international standard definitions in the performance levels of rotation behaviour.
Seismic Fragility Analysis of Vertically Irregular Steel Framed Buildings
Authors: Shah Brij M , Davis Robin , Nanda Kumar C G
Published: October 2020

Disaster mitigation of the country requires the data of fragility curves for various typical buildings. As the number of steel buildings in the cities is increasing, development of seismic fragility curves of steel buildings are also the need of the hour. This study discusses the fragility curves and damage index functions of a 7-storey regular and irregular steel-framed buildings subjected to different earthquake ground motions. Each building was designed based on the codes, IS 800 (2007) and IS 1893 part 1 (2016). Time History Analysis of various vertically irregular framed buildings was performed and displacements of each floor were obtained. Inter-storey drift ratio and spectral acceleration at fundamental period are taken as damage parameter and intensity measure for deriving the fragility curves. The probabilistic seismic demand models for typical stiffness and mass vertical irregular buildings were developed. Steel framed buildings with ground storey open were found to be the vertically irregular building which is the most vulnerable out of all the selected vertical buildings.
ANN Based Design Parameter Estimation for Structural Systems
Authors: Nagesh M , Balu A S
Published: October 2020

Estimation of the probability of failure of multi-dimensional structural systems is expensive from the computation perspective. To decrease the burden of computation, one can use simple approximation methods like Surrogate models, Kriging model, Support vector machine, Artificial neural network, and more based on the suitability for the problems. In Surrogate or Response surface modeling, the limit state function of any system is suitably approximated by making use of known mathematical models like polynomials, exponentials, etc. During the construction of surrogates, variables in the model should be well known prior to the approximation. In practical consideration, the design parameters are the unknowns that need to be evaluated before reliability-based design. Inverse Response surface procedure is proposed in the paper to address the above-mentioned issue. The procedure developed is the combination of adaptive Response surface method with appropriate experimental design i.e. Halton low discrepancy sequence sampling technique for evaluating the probability of failure or reliability index and an Artificial neural network is utilised as an inverse reliability procedure for design optimisation. The method gives an accurate result and the efficiency is increased for the same number of iterations in comparison to the work of David Lehky and Martina Somodikova [1] with Latin hypercube sampling as experimental design.
Modelling and Optimal Design of Thick-Walled Composite Pipes under In-Service Conditions
Authors: Wang T , Menshykov O , Menshykova M , Guz I A
Published: October 2020

The current study is focused on the stress-strain analysis of multi-layered thick-walled fibre reinforced composite pipes under torsional load. Three-dimensional elasticity solution has been obtained and Finite Element Method model has been developed to predict the stress-strain distribution and compute the Tsai-Hill failure coefficients. The models have been validated by comparing with the results available in the literature. As a numerical example the composite pipe subjected to pure torsion load has been considered. The effects of the torque magnitude and layers’ thickness for specific pipe lay-ups have been investigated, and the appropriate engineering conclusions and design suggestions have been reported.
Comparative Study of Beam Theories on the Effect of Span-Depth Ratio for Symmetric and Un-symmetric Loadings
Authors: Gaur Akash , Dhurvey Priyanka
Published: October 2020

In the present work, a comparative study is done between Shear-indeformable (Euler-Bernoulli) model and Shear-deformable (Timoshenko) model for two different types of beams (simply supported and fixed beam) under uniformly distributed loading condition and analysed for different Span-Depth ratio (L/D). For un-symmetric loading, a simply supported beam subjected to external point moment is also analysed for different L/D ratios to check the behaviour of beam. Transverse Displacement is taken as a yardstick. Shape functions for Euler-Bernoulli and Timoshenko beam models are developed in MATLAB software by using the Finite Element Method for calculating deflection at different points on the beam. It was observed that for large L/D ratio, the deflections are same for both the beam theory models but as L/D ratio decreases, the deflections for both the beam theories vary from each other. For small L/D ratio, Timoshenko beam model gives more accurate results, since the Timoshenko beam theory is a higher order beam theory than the Euler-Bernoulli beam theory, it is known to be superior in predicting the response of the deep beam.