bluuebunny/crossref_metadata_2025 huggingface dataset:
Bit-Serial Logical Operation Processor Based on Shift Registers and Mealy Machine
Authors: Shen Luyi
Published: February 2023

With the rapid development of modern processors, logical operation processors could not only process data by logical operations but also store the data. The logical operation processor designed in this paper will be the bit-serial logical operation processor. In order to build the processor, four units should be designed first: the Shift Register Unit, Computation Unit, Routing Unit, and Control Unit. Among them, the Register Unit and the Control Unit are the most important. For the Register Unit, there will be two 4-bit registers. For the Control Unit, this circuit will implement a Mealy machine to determine the output and state of the circuit. The input to the processor will first get into the Control Unit, and then the data given outside will be stored in the Shift Register Unit and will be input to the Computation Unit and finally returned to the Shift Register Unit after Routing Unit. Since the processor is operating in series, the Control Unit and the Shift Register Unit should work synchronously.
Design and implementation of electrical engineering experiment based on the Arduino platform
Authors: Chen Yuxuan , Li Yi , Shi Xinyi , Zhang Chengyi
Published: February 2023

Arduino platform is a new hardware and software combination platform that is widely used, flexible, easy to operate, and rapidly developing. In this paper, the design and implementation of the DC chopper circuit were conducted based on the Arduino platform. Firstly, the power signal and trigger signal are output in the form of programming on the Arduino platform, and the rest of the circuit is built on the breadboard in the form of hardware. Finally, the design waveform is obtained. This paper introduces the basic working principles of four power conversion circuits, conducts circuit simulation on MATLAB software and obtains the ideal output waveform, and uses C language programming to trigger control signal generation, generates corresponding electrical signals through compilation and USB wire transmission to Arduino controller, and builds relevant circuits. This paper makes use of the advantages of the breadboard, fully combines the theoretical knowledge and circuit connection, and finally observes the output waveform through an oscilloscope, and compares the waveform of the actual circuit with the simulation results of MATLAB.
Urban Intersection Simulation and Verification via Deep Reinforcement Learning Algorithms
Authors: Liao Hanlin
Published: February 2023

Reinforcement Learning (RL) uses rewards to have iteration and update the next state for training in an unknown and complex environment. This paper aims to find a possible solution for the traffic congestion problem and train four Deep Reinforcement Learning (DRL) algorithms to verify the urban intersection simulation environment in the different discussed dimensions, including practicability, efficiency, safety, complexity, and limitation. The experiment result shows that the four DRL algorithms are efficient in the RL intersection simulation. This paper has succeeded in verifying this RL environment in the comparison and expands the experiment with three conclusions: The agent can train by Deep Q-network(DQN), DoubleDQN, DuelingNet DQN, and Categorical DQN algorithms to be practical and efficient. As the experiment results show, DuelingNet takes less time to finish the training, and Categorical DQN has reduced the collision rate after a while. However, the RL simulation environment lacks complexity, causing limitations in solving more complex problems, including the lack of simulation of pedestrian behaviors and the prediction of emergency events. This paper recommends creating a more complex urban intersection simulation that includes exceptional cases for the RL agent environment and more traffic pressure for the intersection to improve the faster and safer response in future automatic driving.
Conduction Mechanism and Influencing Factors of SiC MOSFET
Authors: An Yiping , Wang Yifan , Wu Yujin , Yang Jiazhen
Published: February 2023

With the rapid development of the microelectronics industry, power semiconductor devices are getting more and more attention from the industry. At the same time, discussions on the application of power semiconductor materials have never stopped. Over the years, SiC material has stood out because of its superior physical characteristics. Compared with traditional Si MOSFET technology, SiC MOSFET technology has better physical characteristics in some aspects and has a broader market prospect. This paper introduces the conduction mechanism of SiC MOSFET and its performance factors, and the volume effect, bias temperature instability, and threshold voltage drift of SiC MOSFET are discussed. This paper is helpful in understanding the broad application prospects of SiC MOSFET technology and the difference and reform between SiC MOSFET and traditional Si MOSFET.
Working principle and characteristic analysis of SiC MOSFET
Authors: Yao Jifan
Published: February 2023

Power semiconductor devices are frequently used in the electronic and power industries. As the third-generation broadband gap power semiconductor devices, silicon carbide devices have attracted extensive attention. This paper introduces the internal and external structure of SiC MOSFET in detail and analyzes the basic working principle of SiC MOSFET and the electrical characteristics of each stage in the conductive process. By analyzing the theoretical calculation method of threshold voltage under body effect and the relationship diagram drawn by specific experimental test results, it is proved that the increase of body effect will lead to the decrease of the threshold voltage. Two main reasons for BTI characteristics are explained: the energy band shift of the SiC/SiO2 interface is small, and there are many charge traps at SiC/SiO2 interface. Finally, the theoretical calculation method of threshold voltage and the influence principle of threshold voltage drift caused by SiC/SiO2 interface charge: interface trap Qit, oxide trap Qot, movable ion Qm and fixed charge Qf are analyzed. The research on the basic principle and important characteristics of SiC MOSFET in this paper have important reference significance for improving the reliability of SiC MOSFET devices.
Limit shape for infinite rank limit of tensor power decomposition for Lie algebras of series
so2n+1
*
Authors: Nazarov Anton , Nikitin Pavel , Postnova Olga
Published: February 2023

We consider the Plancherel measure on irreducible components of tensor powers of the spinor representation of

s
o

2
n
+
1

. The irreducible representations correspond to the generalized Young diagrams. With respect to this measure the probability of an irreducible representation is the product of its multiplicity and dimension, divided by the total dimension of the tensor product. We study the limit shape of the generalized Young diagram when the tensor power N and the rank n of the algebra tend to infinity with

N

/

n

fixed. We derive an explicit formula for the limit shape and prove convergence to it in probability. We prove central limit theorem for global fluctuations around the limit shape.
Subsurface Investigation on Federal Route Failure at Pengkalan Raja, Pontian, Johor
Authors: Zainuddin N E , Zainal Z , Nagendran S K
Published: February 2023

Road settlement is one of the major problems that often occurs in soft soil ground areas. The combination of destructive test method (trial pit, Standard Penetration Test (SPT) and borehole) and non-destructive method by using seismic refraction, electrical resistivity tomography (ERT) and ground penetrating radar (GPR) were performed to identify the factor causing the tension cracks and road differential settlement. The study area selected is at Section 39 to 50, Federal Route (FT005) Johor Bahru to Malacca (Pengkalan Raja, Pontian, Johor) because of the severe road condition which may cause an accident to road user. This paper presenting the result of destructive and a non-destructive test. From results of borehole, seismic, and ERT, the road was underlaid by 7-12m of a soft compressible layer. The GPR image showed the existing of concrete slab below the road has deviated from its original position and may not function as a foundation of road. In conclusion, the combination of destructive and non-destructive method is best approach in identifying the underground failure because it is the fastest solution, economical and suitable in area of high volume of traffic.
How Artificial Intelligence Changed the Construction Industry in Safety Issues
Authors: Razi PZ , Sulaiman SK , Ali MI , Ramli NI , Saad MSH , Jamaludin O , Doh SI
Published: February 2023

In recent years, the development of machine learning in construction as well as the preparation of appropriate software aims to provide improved solutions to potential safety hazards and risks within the construction environment. However, the fatalities and injuries in construction sites still happened frequently, and the high numbers of accidents and casualties make construction work the most hazardous occupation. This study aims to analyze the prioritize of artificial intelligence (AI) important factors in construction safety using the AHP method. Construction safety practitioners were selected as the respondent. The hierarchy was established consisting of five (5) factors, which were subsequently categorized into twelve (12) sub-factors. With 25.43 percent, jobsite was determined to be the most significant AI element in construction safety, followed by technology component with 25.37% and human error with 22.76%. The subfactors that prioritize are noticed to safety officers when workers disregard safety on the construction site with 69.21%, cloud computing technique, inspecting, controlling, and training with 60.04%, and AI in construction safety can predict the possible issues with 14.29%. The findings of this study can help software developers in determining the level of priority for the use of AI in the safety aspect of construction sites.
Multicriteria Decision Model for Road Construction Project
Authors: Ramlay SN , Razi PZ , Ali MI , Ramli NI , Saad MSH , Jamaludin O , Doh SI
Published: February 2023

Construction of roads plays an important role in linking one area to another, and also acts as a substance for the local economy. However, the limitation of study on the project performance towards the road infrastructure construction project requires more precise attention. Thus, it requires distinct responsiveness from contractors to evaluate and cope with the risks. This study aims to identify the project execution risk factors involved in the road construction project, reference to a current case study from a federal government project Public Work Department (PWD) on the East Coast of Malaysia: Upgrading 14.7 kilometre (km) federal road from the Pekan town to Sungai Miang. This study will begin with the identification of the project execution risk factors, utilizing an extensive review of the literature. Next, the gathered risk factors will go through a pilot phase validation interview with road construction experts from the public work department (PWD) and also construction practitioners that are involved directly in the project case study. Findings found seven (7) main project execution risk factors involved in the road construction project, which include resource risk, land acquisition issue, project management issue, technical risk, service utility issue, unforeseen ground condition, and force majeure risk. Among the seven (7) factors twenty-one (21) project execution risk sub-factors, were further explored that are crucial to the project. The main contribution of this study is the final multi-criteria decision model obtained from literature searching cross-referenced to the real case study that may be beneficial to the road construction project team specifically.
The growth and development of Chlorella Vulgaris in the batch culture system
Authors: Zaini N , Kasmuri N
Published: February 2023

Phytoremediation technique using microalgae has been critically explored nowadays. This method has been employed to achieve cleaner production for a sustainable future. Moreover, phytoremediation imprints green technology as a promising alternative in long–term best management practices. Here, the research aims to cultivate the microalgae, in this case, Chlorella Vulgaris, in the batch culture system using three different mediums (wastewater effluent from wastewater treatment plant UiTM Dengkil, synthetic wastewater and nitrification medium). Optimum conditions such as an aeration system and an ambient environment with sufficient sunlight have been provided for microalgae growth. Here, the performance of Chlorella Vulgaris on the uptake of ammonia-nitrogen, nitrite-nitrogen, nitrate-nitrogen, and phosphorus for the three mediums was observed daily until 14 days. From the results obtained, synthetic wastewater has been considered the suitable medium for the uptake of Chlorella Vulgaris. It can be observed that the percentage removal for nitrate-nitrogen, nitrite-nitrogen, ammonia-nitrogen, and phosphorus were 54.84%, 80.38%, 91.03%, and 67.21%, respectively. There is also a substantial increase in Chlorella Vulgaris growth in 14 days of cultivation in the synthetic wastewater medium. Moreover, it can be expected that the days of observation can be extended to achieve higher growth of Chlorella Vulgaris. Thus, it can portray a clearer insight into the performance of the microalgae for the degradation of the pollutants concerns.
Detection and Maintenance for Railway Track Defects: A Review
Authors: Li J. , Doh S. I. , Manogaran R.
Published: February 2023

Steel rail has been at the heart of rail transportation systems for nearly a hundred years. With the rapid development of railway transportation, the steel rail operates in high-speed and heavy-duty operating environment. Steel rail is prone to damages; thus, frequency inspection and maintenance is required to prolong the lifespan of it. Failing to proper periodical inspection and maintenance shall result to accidents which cause injuries and fatality, high repair cost and loss of public confidence. Despite advances in inspection and maintenance technology in railway engineering, the ever-increasing demand for services has resulted in railway failures continuing to be a significant economic burden and jeopardizing the safe operation of railways. This paper reviewed the common defects of rails, the steel rail treatment methods and the application of new inspection equipment.
The Application of Lean Construction Concept in Multi-Storey Building Construction Project
Authors: Azzahra F , Rani H A , Erina M
Published: February 2023

Every construction project cannot be separated from various obstacles or failures. For this reason, it is necessary to improve planning using the lean construction method. The problem in this research is how to apply lean construction concepts, what factors can cause waste, and whether there are significant differences between the perceptions of contractors, supervisory consultants, and owners on the factors that cause waste to occur in fire station building construction. The purpose of this study was to analyze the application of lean construction and analyze the factors that cause waste and the differences between the perceptions of contractors, supervisory consultants, and owners. This study employs both quantitative and qualitative methods. Based on the analysis of observations made, the application of lean construction that was reviewed has started to be implemented, and there are some that have not been implemented properly, such as checking for safety, increasing visualization, and first run studies, so that it can cause waste. Descriptive analysis shows that only a small part of the waste factor with data interpretation intervals is found, namely waiting time for instructions. The results of one-way ANOVA analysis showed that there is no significant difference between the perceptions of contractors, supervisory consultants, and owners of the factors that cause waste.
Exploring the barriers in implementation of qlassic in Malaysian construction industry from the perspective of contractors
Authors: Zahrizan Z , Affendy O.M , Khalimi Johan A H
Published: February 2023

Construction industry is one of the largest contributors to the economy in Malaysia. Many studies have showed the significant of the construction industry contribution but the issues of properties buyers especially still apprehensive in the industry. National House Buyers Association (HBA) has recorded thousands of complaints from buyers who were not satisfied with the condition of their new properties or the way defects were rectified. The main objectives of QLASSIC is to increase the quality of building but after more a decade the implementation of QLASSIC still lagging behind and there are still many developers and contractors are reluctant to use QLASSIC approach in their projects. Therefore, the main goal of this study is to explore the factor hindering the implementation of QLASSIC in Malaysia especially from the contractors’ perspective. Questionnaires were used as research instrument for collecting data information, then the data were analysed by using Relative Importance Index (RII). From the analysis, it is found that the main factors that could hinder the implementing of QLASSIC are; lack of coercive and mimetic pressures, lack of capabilities of staff in perform QLASSIC assessment practice due to minor size and type of organisation influence in adopting QLASSIC, higher cost to undergo training to operate QLASSIC’s tools and minimal benefits gained when adopting QLASSIC. In conclusion, it’s important to tackle the actual factors hindering the implementation of QLASSIC in Malaysian construction industry. Concurrently, every parties in the construction industry should play their roles in promoting the use of QLASSIC in their construction project. Besides that, the government has to make a new strategy in promoting the use of QLASSIC by providing incentive such as tax rebate if the contractors used QLASSIC assessor to access their projects.
Application of BIM in construction site safety: Systematic review
Authors: Shukri Najwa Syazana Mohd , Aminudin Eeydzah , Yap Loh Seng , Zakaria Rozana , Hamid Abd Rahim Abd , Kiong Mak Tuck
Published: February 2023

Construction safety has become and establishment ever since decades. Construction industry especially workers involve in many activities that may expose them to serious hazards. However, with the transformation of current development in technology, safety has become vital especially the needs in improvement of its application on site via digitalization. The exploration on the needs of safety especially in Building Information Modelling has become crucial and there is a need for the application especially the digital twin. The construction industry needs to improve the safety performance by new technology. Building Information Modeling is one of the technologies that are being explored recently. Hence, this paper aims to obtain a comprehensive review especially on the current trend of analysis based on current practice of emerging technology that applied in current practice. Methodology of this paper by info analysis and VOS Viewer. There were 11 different terms were used to obtain the relevant literature including Scopus, Google and books guideline. After data cleaning, there’s almost 371 journal articles reviewed in between Jan 2011 and Aug 2021. There are 4 steps of framework being proposed which are analysis on the source of title, researcher, co-occurrence keyword and discussion. Hence from the results of co-occurrence based on the results shows that 21 keywords, as for the researcher were top 10 highlighted. It can be concluded that Building Information Modeling (BIM) and safety construction has the most citation for the current trend of research. Besides it is expected that this study has the potential outcome of research as references for next study on BIM and safety.
Flexural Behaviour of the Two-Way Spanning Reinforced Concrete Slab Using Spherical Plastic Bubble Balls
Authors: Muhamad Khairussaleh N A , Omar R , Mat Aris S , Mohd Nor M F , Mohd Saidi M A , Nik Mohd Mahari N M A
Published: February 2023

The use of conventional reinforced concrete in the construction industry increases each year, especially in developing countries. However, the concrete content, particularly cement production contributed to the greenhouse gas emission subsequently increase to climate change. Thus, the reinforced concrete slab containing high-density polyethene (HDPE) hollow spherical plastic bubble balls also known as bubble deck slabs were introduced for sustainable construction. This type of slab forms a slab that has less concrete volume compared to the normal solid reinforced concrete slab. Although this unique system can facilitate up to a 50% longer span compared to the conventional reinforced concrete solid slab, yet, it can cause the performance of the slab structure such as flexural and shear capacity may be affected due to the thirty to forty per cent of fewer concrete volumes. Hence, this paper studies the comparison of the performance of the two-way supported slabs; reinforced bubble deck slab and normal solid reinforced concrete slab after being subjected to the area loading. The square slabs are 1200mm by 1200mm in width and length with a thickness of 235mm. The investigations of the experiments included flexural strength, bending stiffness and load-deflection behaviour due to the impact of the area loading. Also, the crack propagation and crack pattern which differs also was shown for each type of slab system, especially in shear strength.
Plotting Position for Low Flow Frequency Analysis at Jempol River Streamflow Station
Authors: Samat S R , Othman N
Published: February 2023

Low flow frequency analysis is an important technique for calculating the probability of river flow availability during crucial low flow seasons, such as drought. It is also useful to predict the low flow information of a river in volume and frequency for future planning and construction of water resource projects since the low flow has a significant impact on water quality, water supply, and river sustainability conditions. Therefore, this study was performed to determine the low flow frequency analysis of the Jempol River streamflow station using Weibull and Gringorten plotting position formulas. The average recurrence interval (ARI) of 2-, 5-, 10-, 25-, 50-, and 100-year were determined based on 18 years of historical streamflow data. The study illustrates the annual minimum flow magnitude of 1-, 4-, 7-, and 30-day durations for the study area. It shows that the Gringorten formula tends to give higher estimation values up to 18% compared to the Weibull formula when the flow duration increase. Therefore, the outcome of this study could be used in the future for any project related to the low flow information of Jempol River.
Mechanical Behaviour of Self-Compacting Concrete Using Ceramic Waste
Authors: Meillyta Meillyta , Wahyuni Wahyuni , Fahmi Zul
Published: February 2023

The use of Self Compacting Concrete (SCC) which has high workability is the current choice to facilitate casting work so that it can pass through denser reinforcement areas without compaction. The rapidly increasing demand for concrete can cause damage to nature due to the overexploitation of minerals used for concrete such as crushed stone and lime. Construction waste can be an alternative to substitute the use of natural coarse and fine aggregate and an option to reduce gas emissions resulting from processing construction materials such as crushing work and cement production. Moreover, it can increase the efficiency of waste. In this study, ceramic waste is used as a substitute for coarse aggregate, which has the same characteristics as natural aggregate and is usually only dumped in landfill. This study aims to determine the mechanical behavior of SCC using ceramic waste as coarse aggregate substitution with a diameter of 9,52 mm. The mix design uses the Indonesian standard, SNI 7656-2012 with a maximum coarse aggregate size of 9.52 mm and Sika viscocrete 1003 as a superplasticizer. The concrete specimen is 15 cm in diameter and 30 cm in height cylinder of as many as 25 specimens. Design concrete strength is f’c = 25 MPa at 28 days old. The variation of the coarse aggregate substitution of ceramic waste is 0%, 25%, 50%, and 75%, and the 1.5% superplasticizer by the weight of cement. It is obtained that the maximum compressive strength of SCC is a variation of 50% ceramic waste, 25.98 MPa. It showed that the compressive strength did not experience a significant increase, which was only 0.06% increase from the design concrete strength. The stress value also showed a slight increase of 50% ceramic waste variation at 9.42 MPa with a 0.00254 strain value. The modulus of elasticity of concrete at maximum stress is 30,045.89 MPa. It can be concluded that ceramic waste can be used as a substitute for coarse aggregate in SCC. Although it cannot significantly increase the strength of the concrete as well as its stress and modulus of elasticity, ceramic waste substitution for natural aggregate in concrete can minimize the exploitation of minerals in nature and the strength also can exceed the design concrete strength.
Progress Monitoring at Construction Sites Using UAV Technology
Authors: Kaamin Masiri , Fahmizam Muhammad Afiq Fawwaz , Jefri Ahmad Syazwan , Sharom Muhammad Hafiz , Kadir Muhammad Azraie Abdul , Nor Ahmad Hakimi Mat , Supar Khairi
Published: February 2023

One of the monitoring jobs in construction projects is conducting monthly surveys for monitoring the work done on the site. However, monitoring progress common for large-scale construction sites is arduous and time consuming. The manual method for monitoring a project is by taking pictures at the construction site using ordinary digital cameras that lacking in ability to capture the overall condition, especially for building structures that are too high or construction sites that are enormous. This study used UAV technology to help control and monitor the progress of monthly construction work at a construction site through visual image recording of the entire construction site. The study was conducted by recording images periodically for three months, which were then processed through Pix4Dmapper peripherals. This effort used photogrammetric UAV technique to achieve the main purpose. The study area was monitored to distinguish active and inactive areas from the first month to the third month in which orthomosaic images were taken to be analysed through Global Mapper software. The study proves the feasibility of using UAV as an alternative in visual monitoring and facilitating project management, as it is able to produce a more detailed view of the entire construction site area for each progress.
Editorial
Authors: Furgiuele F. , Bonora N , Quaresimin M. , Meneghetti G. , Livieri P
Published: February 2023

The Italian Association for Stress Analysis (AIAS) was founded in 1971 by researchers from academia, research centers, and industry. AIAS was intended as a community where to discuss, share, and develop scientific knowledge related to all technical aspects of stress analysis. In the years, from an initial focus on experimental techniques, AIAS contributed considerably to the development of modern numerical methods and computational techniques for mechanical engineering design. In 2015, AIAS turned in the Italian Scientific Society of Mechanical Engineering Design.

Today, AIAS is an institutional partner that supports the instances from academia in the subject area of mechanical engineering design. Every year, AIAS organizes a technical conference offering the possibility to present research updates, share new ideas, and foster collaborations. The AIAS conference has become a fundamental event for all those interested in current developments in mechanical engineering design and stress analysis, where to meet researchers, testing equipment, and software developers.

The 51st AIAS Conference edition was held in Padova, Italy again in presence after two years of online-only events due to the COVID-19 pandemic.

The response of researchers and students has been outstanding: over 200 oral contributions have been presented during the three days of the conference, with four parallel sessions. In addition to the thematic sessions on AIAS traditional subjects, special sessions on additive manufacturing, energy methods for structural analysis, circular design in mechanical engineering, and mechanical behavior under extreme conditions, have been successfully organized with the contribution of the AIAS technical committees.

Among all contributions presented at the conference, 48 have been selected to be published after peer review, in this volume. This was made possible thanks to the active participation of all AIAS members, to the work of the AIAS Scientific Committee and Conference Papers Review panel (Profs Giovanni Meneghetti, AIAS Scientific Coordinator, Luciano Afferrante, Francesco Bucchi, Filippo Cianetti, Enrico Armentani, Marco Sasso). Their outstanding contribution is gratefully acknowledged.

Disclaimer

AIAS2022 Conference was held in presence on Sept. 7-10, 2022. Presentations were arranged in four parallel sessions with a time slot of 15 min assigned to each presenter. Approximately 250 participants attended the conference during the three days event. All sessions have been continuously monitored by the organizers to provide technical support. The conference ran smoothly, and the participants’ feedback was very positive.
Vibro-Acoustic Modulation with broadband pump excitation for efficient impact damage detection in composite materials
Authors: Loi G , Marongiu G , Porcu M C , Aymerich F
Published: February 2023

In the past few decades, the need for efficient and reliable Structural Health Monitoring strategies has led to the development of several approaches for damage detection and characterization purposes. Among them, the Nonlinear Vibro-Acoustic Modulation (VAM) exploits the modulation arising from the interaction of two concurrently applied driving waves, namely the probe and the pump excitations, in the presence of nonlinear scatters such as cracks and defects. Therefore, the VAM provides information on the emergence of internal damage by extracting the nonlinear modulated components of the response of a damaged system. Originally proposed for granular media, the method has shown to be effective in detecting the presence of defects also in metals and composite materials. Nonetheless, its efficacy is highly affected by the excitation frequencies, which are usually chosen among the system resonances. The need for a preliminary modal analysis and, at once, the risk of selecting pump-probe frequency combinations with low sensitivity to damage may make the procedure time-consuming and not fully reliable, preventing the VAM technique from being widely accepted as a robust monitoring tool. To overcome these limitations, a broadband excitation may be used. This study assesses the effectiveness of the VAM technique when a combination of a frequency-swept pump excitation and a mono-harmonic probe wave is applied to drive the sample. Experimental tests were conducted on a composite laminated beam mounted on an electrodynamic shaker and tested in both pristine and damaged conditions. Low-profile surface-bonded piezoceramic transducers were used for both probe excitation and sensing. Barely visible impact damage (BVID) was introduced in the composite beam to examine the potential of the approach for the detection of very small, localized damage. The results show that the use of VAM with a broadband low-frequency excitation may be an effective option for identifying nonlinearities associated with typical damage occurring in composite structures.
Fatigue health monitoring of AISI 304 notched specimens by means of thermographic analysis and UT-based measurements
Authors: Panella F W , Pirinu A , Saponaro A , Nobile R , Rucco R , Renna V
Published: February 2023

The damage accumulation and the cracks development due to fatigue loads are the main failure mechanisms that occur in metal structures. Therefore, the prediction of structural damage is critically important for the safe and reliable operation of complex engineered systems. In the present work, the evolution of fatigue damage was monitored by infrared thermographic and ultrasonic measurements by means of piezoelectric sensors (PZTs) applied to a batch of notched specimens in AISI 304 stainless steel. Concerning the ultrasonic data, a linear and non-linear frequency study was carried out on the data acquired at various steps during the fatigue life through an appropriate MATLAB analysis algorithm based on the Fast Fourier Transform (FFT). In details, the proposed damage parameters related to thermal variations and the peak-to-peak signal voltage (Vpp) were considered to evaluate the fatigue damage process. Regarding the IRT technique, the thermographic monitoring inspection is implemented with measurements processed in MATLAB to estimate damage indices related to the fatigue damage of the same specimens. The results of the thermal analyses were finally compared with the data of the ultrasound measurements obtained to provide complementary information on the prediction of fatigue damage. The experimental results indicate an interesting increase in the proposed damage parameters that could be associated with an irreversible change due to fatigue damage at the notch tip. The final propagation phase of the crack, instead, is characterized by a quick data variation in agreement with the stiffness reduction. The applied Monitoring strategies has proved efficient for detecting damage induced by fatigue in metal materials.
An innovative experimental energy-based approach for the life prediction of notched details
Authors: Crisafulli D , Foti P , Santonocito D
Published: February 2023

Fatigue assessment of mechanical components can be very challenging due to the presence of macroscopic defects and notches. However, local approaches as the Stain Energy Density, have shown how the fatigue resistance is strictly related to the local stress field near the notch tip and not on the overall dimensions of the component. It is necessary to know some peculiar material’s parameters to apply those local approaches. A short way to obtain such parameters can be to apply Thermographic Methods, such as the Risitano’s Thermographic Method and the Static Thermographic Method, monitoring the energy release during stepwise fatigue and static tensile tests. In this work, experimental tests were performed on plain and double edge steel notched specimens. The SED method has been applied through finite element models, with the easy application of the volume-free procedure, to evaluate its trend at several stress levels. The analysis of the energy release and of the local averaged strain energy density during a static tensile test may be adopted as a novel approach to relate the local stress state with a macroscopic stress value that introduce in the material the first micro plasticization leading to the failure of the component.
An analysis of the dependence of the material length parameter a0 on the stress ratio
Authors: Atzori B , Rigon D , Meneghetti G
Published: February 2023

Safe life approaches in notch fatigue of metallic components rely on the knowledge of the material response to fatigue stresses at notches, which is typically quantified by a material-dependent length parameter. As a general material behaviour, such material parameter depends on several factors and one of the most important of them is the mean stress. The present study is focused on the El Haddad-Smith-Topper material length parameter a0 for analysing under which circumstances and to which extent it may vary with the applied mean stress or stress ratio. The analysis starts by considering the broader problem of the mean stress influence on the fatigue limit of plain material, blunt and sharp notches and cracks. Eventually, an analysis of previous sets of experimental data on wrought steels led to simple relations for estimating the a0 parameter at different stress ratios on the basis of the sole Vickers Hardness
Correlation between Preload and Geometric Characterisation of metal meshes for space antenna reflectors
Authors: Salvini P , Marotta E
Published: February 2023

The paper deals with digital image processing techniques to analyse the shape of the main voids in the metallic mesh of large deployable antennas. The shape of the holes in the mesh influences the electromagnetic performances as the working frequencies and the polarisation effects. The analysis compares two types of mesh subjected to a series of equal loads in two directions; for this task, a dedicated testing machine is used. The paper presents an approach to defining an effective and averaged repetitive pattern. Thus, a statistical point of view of the entire mesh is given, applicable to studying the behaviour of a full reflector, to avoid being affected by local texture defects.
Analysis of Wind Turbine Pitch 4-Point Contact Bearing
Authors: Porziani S , Biancolini M E , Brutti C
Published: February 2023

In the field of renewable energy source, the wind power is certainly one of the most important and therefore the industrial and research community are devoting increasing attention to the design, construction, management and maintenance of wind turbines. Due to the relevance, technical, economic and social of this type of installation the correct maintenance is actually a crucial challenge. As in all mechanical engineering applications, numeric models, FEM based, are widely used during both the design step and monitoring on site. In fact, in the frame of Structural Health Monitoring (SHM), the availability of a Digital Twin is fundamental to interpret the signals coming from the sensors and to check the state of wear and the progression of any damage. In general, this numerical tool must have a good accuracy and a great rapidity of response. For this reason it is essential to develop condensed and reliable models of the main elements able to represent the real behaviour of the component without excessively increasing of computational costs. One of the most important element is the pitch variation slewing bearing, which allows the optimal wing orientation. Unfortunately, a complete numeric model of the bearing requires very large dimension and so the real time reply, necessary to SHM, is difficult. In this paper, to overcome this problem, a new simplified model is proposed to represent the array of spheres and its contact condition with the rings of the bearing. The new approach is based on the adoption of a toroid-shaped element replacing the rolling elements. To study this solution, a full-detailed model of a typical slewing bearing for pitch variation has been used to properly set up the contact model and to tune the properties, geometrical and elastic, of the equivalent toroidal body. The main feature of this approach is that, with a relatively low calculation effort, the deformation behaviour and the stress state of the elements connected to the bearing is available in an easy and accurate way. Then, the comparison in real time of the numerical results with the corresponding experimental ones from the site allows to deduce initiation and growth of a damaging process.
Scooter Tire Pressure Influence on a Hard Braking Manoeuvre
Authors: Failli M , Fontanelli T , Paoletti E , Bartolozzi M , Berzi L , Savino G
Published: February 2023

The mortality of road accidents quadruples when, in addition to motorists, a motorcyclist is also involved. The higher mortality is influenced by the greater exposure of the rider to injuries during the impact. This problem can be mitigated by reducing, even slightly, the impact’s speed. Bench tests carried out by previous studies showed a considerable influence of the inflation pressure on the properties of motorcycle tires. It could therefore have significant effects on the deceleration achievable under braking. This study aimed to evaluate the effect of inadequate tire inflation pressure (excessive or insufficient) on the average deceleration achievable during a hard braking manoeuvre performed only with the rear wheel and with ABS intervention. Experimental tests were carried out on a Piaggio Beverly S 300 in a controlled road environment closed to traffic. Different inflation pressures of the rear braking tire were tested during multiple runs. The data were acquired through a smartphone used as an IMU. At the nominal pressure of 2.4 bar the measured average deceleration was 3.69 m/s2 (SD = 0.12 m/s2). When increasing the pressure to 3.0 bar and decreasing it to 1.8 bar the average deceleration was reduced respectively to 3.67 m/s2 (-0.8%, SD = 0.10 m/s2) and 3.59 m/s2 (-3.0%, SD = 0.16 m/s2). The reduction in achievable deceleration was partly mitigated by the reduced load transfer on the rear tire, which partially compensated for the reduction of the braking force coefficient. The results showed that a moderate inflation pressure variation on the rear braking tire modestly influences the achievable average deceleration.
Modelling, testing and validation of an innovative AEB control logic on a Hardware-in-the-loop test bench
Authors: Veneroso L , Alfatti F , Annicchiarico C , Capitani R
Published: February 2023

AEB, autonomous emergency braking, is an active safety system designed to prevent vehicle frontal collision. The most diffused AEB systems are based on simple Bang Bang control logic, which could often avoid, or at least mitigate collision effects, but their effectiveness can still be improved by increasing system repeatability. The aim of this study is to model and test an innovative AEB control logic that will increase system reliability by compensating for the non-immediate response of the braking system to braking requests. Using a hardware-in-the-loop test bench with two different braking systems implemented, the new controller was tested simulating the CCRs and CCRm scenarios, used by Euro NCAP for AEB system assessment. By compensating for the delay introduced by the response of two different braking systems, the innovative control logic stops the VUT, Vehicle Under Test, at the desired safety distance from the GVT, Global Vehicle Target.
Crack propagation in viscoelastic finite-sized solids: theory and experiments
Authors: Violano G , Carolis S De , Palmieri M E , Carbone G , Tricarico L , Demelio G P , Afferrante L
Published: February 2023

The problem of crack propagation in viscoelastic materials is of great interest given the numerous engineering applications of such materials. Due to viscoelasticity, even the study of the basic Mode I opening represents a tricky theoretical challenge. Indeed, existing theories adopt important approximations such as i) simplistic constitutive behaviour, ii) steady-state crack propagation, iii) infinite domain of the system. In this work, we revise the theory of Persson & Brener for systems of infinite domain; specifically, we propose a solution to take into account size effects in a viscoelastic plate. The theory allows to consider the realistic constitutive behaviour of viscoelastic materials and to predict the dependence of the energy release rate with the crack tip speed. Comprehensive experimental investigations are performed to corroborate our theoretical predictions. First, dynamic mechanical analysis (DMA) is performed to characterize the complex viscoelastic modulus of PolyTetraFluoroEthylene (PTFE). Second, tensile tests are carried out on cracked PTFE samples, and pictures are recorded with an image acquisition system. Moreover, a point tracking algorithm is developed to measure the crack length and opening displacement. Moving from small to high crack tip speeds, the fracture process becomes less ductile and an increase in the maximum load is observed. In addition, experimental data show that the inclusion of finite-size effects in the theory is crucial for accurately estimating the energy release rate.
Lifetime assessment of the rear axle for an off-road vehicle in a fatigue test bench by means of the Peak Stress Method
Authors: Pelizzari J , Salvagno P , Dengo C , Campagnolo A , Meneghetti G
Published: February 2023

In this study the Peak Stress Method (PSM) has been applied to the fatigue assessment of the welds of an axle equipped in an off-road vehicle. In the fatigue design of welded joints, the PSM is a FE-based method to rapidly evaluate the NSIFs relevant to the opening, sliding and tearing modes by means of the linear elastic peak stresses extracted from the FE model. First, an axle, which consists of a central body and two lateral branches composed by several plates welded to a tube, has been fatigue tested under a vertical load in a test bench designed to replicate the frame-axle interface. Then, an FE model of the axle has been calibrated to simulate the behaviour observed during the fatigue test, where the reaction forces and the strains at pre-defined locations have been considered. Once the FE model has been calibrated, the PSM has been applied to the welds of the axle, taking advantage of an automatic procedure, and the crack initiation location has been estimated. Finally, the theoretical estimations have been compared with the experimental datum.
Effective ways to compare two families of freight trains
Authors: Cantone L
Published: February 2023

The paper shows several use cases of the “relative approach” method, envisaged by international recommendations, for evaluating the safety of two families of freight trains. This is relevant when a decision is needed about a new technology or a new operating mode of freight trains to keep the same safety as existing trains. The paper discusses the heterogeneity of the database of trains and provides examples of the classic application of the “relative approach”, highlighting the effect of train operation. Furthermore, it shows the application to DAC and radio-controlled Traction Units. Finally, it introduces the “Iterative Proportional” algorithm to generate a freight train from an existing one just by changing the hauled mass of each wagon. This algorithm is helpful when the “relative approach” is applied to trainsets having articulated wagons and running with a similar braking regime.
Artificial intelligence based approach for categorization of COVID-19 ECG images in presence of other cardiovascular disorders
Authors: Chaitanya M Krishna , Sharma Lakhan Dev , Rahul Jagdeep , Sharma Diksha , Roy Amarjit
Published: February 2023

Coronavirus disease (COVID-19) is a class of SARS-CoV-2 virus which is initially identified in the later half of the year 2019 and then evolved as a pandemic. If it is not identified in the early stage then the infection and mortality rates increase with time. A timely and reliable approach for COVID-19 identification has become important in order to prevent the disease from spreading rapidly. In recent times, many methods have been suggested for the detection of COVID-19 disease have various flaws, to increase diagnosis performance, fresh investigations are required. In this article, automatically diagnosing COVID-19 using ECG images and deep learning approaches like as Visual Geometry Group (VGG) and AlexNet architectures have been proposed. The proposed method is able to classify between COVID-19, myocardial infarction, normal sinus rhythm, and other abnormal heart beats using Lead-II ECG image only. The efficacy of the technique proposed is validated by using a publicly available ECG image database. We have achieved an accuracy of 77.42% using Alexnet model and 75% accuracy with the help of VGG19 model.