bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance evaluation of digital breast tomosynthesis systems: comparison of current virtual clinical trial methods
Authors: Marshall N W , Bosmans H
Published: October 2022

Virtual clinical trials (VCT) have been developed by a number of groups to study breast imaging applications, with the focus on digital breast tomosynthesis imaging. In this review, the main components of these simulation platforms are compared, along with the validation steps, a number of practical applications and some of the limitations associated with this method. VCT platforms simulate, up to a certain level of detail, the main components of the imaging chain: the x-ray beam, system geometry including the antiscatter grid and the x-ray detector. In building VCT platforms, groups use a number of techniques, including x-ray spectrum modelling, Monte Carlo simulation for x-ray imaging and scatter estimation, ray tracing, breast phantom models and modelling of the detector. The incorporation of different anthropomorphic breast models is described, together with the lesions needed to simulate clinical studies and to study detection performance. A step by step comparison highlights the need for transparency when describing the simulation frameworks. Current simulation bottlenecks include resolution and memory constraints when generating high resolution breast phantoms, difficulties in accessing/applying relevant, vendor specific image processing and reconstruction methods, while the imaging tasks considered are generally detection tasks without search, evaluated by computational observers. A number of applications are described along with some future avenues for research.
Performance evaluation of digital breast tomosynthesis systems: physical methods and experimental data
Authors: Marshall N W , Bosmans H
Published: October 2022

Digital breast tomosynthesis (DBT) has become a well-established breast imaging technique, whose performance has been investigated in many clinical studies, including a number of prospective clinical trials. Results from these studies generally point to non-inferiority in terms of microcalcification detection and superior mass-lesion detection for DBT imaging compared to digital mammography (DM). This modality has become an essential tool in the clinic for assessment and ad-hoc screening but is not yet implemented in most breast screening programmes at a state or national level. While evidence on the clinical utility of DBT has been accumulating, there has also been progress in the development of methods for technical performance assessment and quality control of these imaging systems. DBT is a relatively complicated ‘pseudo-3D’ modality whose technical assessment poses a number of difficulties. This paper reviews methods for the technical performance assessment of DBT devices, starting at the component level in part one and leading up to discussion of system evaluation with physical test objects in part two. We provide some historical and basic theoretical perspective, often starting from methods developed for DM imaging. Data from a multi-vendor comparison are also included, acquired under the medical physics quality control protocol developed by EUREF and currently being consolidated by a European Federation of Organisations for Medical Physics working group. These data and associated methods can serve as a reference for the development of reference data and provide some context for clinical studies.
Optimization of SiGe interface properties with ozone oxidation and a stacked HfO2/Al2O3 dielectric for a SiGe channel FinFET transistor
Authors: Chen Anlan , Li Chun , Yao Qide , Ma Xueli , Li Yongliang , Wang Wenwu
Published: October 2022

In this paper, the optimization of SiGe interface properties for the SiGe channel fin field effect transistor (FinFET) transistor is explored in detail. First, optimal low-temperature ozone oxidation at 300 °C for 30 min was confirmed based on Al2O3/Si0.7Ge0.3 metal-oxide-semiconductor (MOS) capacitors. This is because a higher oxidation temperature and a longer oxidation time can suppress the formation of GeO
X
in the interface layer (IL) and significantly improve the interface state density (D
it). Moreover, compared with the Al2O3 sample, the HfO2 sample can obtain a thinner capacitance equivalent oxide thickness (CET), but it is more vulnerable to deterioration of Si0.7Ge0.3 interface properties because the GeO
X
in the IL is more likely to diffuse into the HfO2 layer. To further optimize the D
it and CET of the Si0.7Ge0.3 MOS capacitor simultaneously, a stacked HfO2/Al2O3 dielectric is proposed. Compared with the HfO2 sample, its frequency dispersion characteristics and D
it have been improved significantly, as the thin Al2O3 layer prevents the diffusion of GeO
X
to the HfO2 layer and controls the growth of GeO
X
. Therefore, a high-quality Si0.7Ge0.3 interface property optimization technology is realized via the development of a low-temperature ozone oxidation (300 °C, 30 min) method combined with a stacked HfO2/Al2O3 dielectric. In addition, a Si0.7Ge0.3 FinFET utilizing this newly developed interface property optimization scheme is successfully prepared. Its excellent subthreshold swing performance indicates that good interface quality of the Si0.7Ge0.3 is obtained. The above results prove that this newly developed interface property optimization scheme is a practical technology for high-mobility SiGe FinFET.
MEMS-compatible structuring of liquid crystal network actuators using maskless photolithography
Authors: Lall Jasleen , Zappe Hans
Published: October 2022

We present a method to structure liquid crystal network actuators based on selectively polymerizing the network without any physical or hard masks in a process compatible with microelectromechanical system (MEMS) technology. The standard glass-cell filling technique is used to generate the actuator films; subsequently, selected areas are exposed to light and thus polymerized to structure the actuators. No further machining, such as laser cutting, is necessary. The polymerization pattern is defined by projection using a digital micromirror device-based optomechanical setup, with a resolution ranging from 1 to 2 mm. These processes are used to structure photothermally and photochemically stimulated actuators, which may thus be fabricated with high throughput and easily integrated with MEMS devices.
Equivalence and superposition of real and imaginary quasiperiodicities
Authors: Cai Xiaoming , Jiang Shao-Jian
Published: October 2022

We take non-Hermitian Aubry–André–Harper models and quasiperiodic Kitaev chains as examples to demonstrate the equivalence and superposition of real and imaginary quasiperiodic potentials (QPs) on inducing localization of single-particle states. We prove this equivalence by analytically computing Lyapunov exponents (or inverse of localization lengths) for systems with purely real and purely imaginary QPs. Moreover, when superposed and with the same frequency, real and imaginary QPs are coherent on inducing the localization, in a way which is determined by the relative phase between them. The localization induced by a coherent superposition can be simulated by the Hermitian model with an effective strength of QP, implying that models are in the same universality class. When their frequencies are different and relatively incommensurate, they are incoherent and their superposition leads to less correlation effects. Numerical results show that the localization happens earlier and there is an intermediate mixed phase lacking of mobility edge.
Fabrication and characterization of air-stable, highly efficient all-inorganic CsPbBr3 perovskite solar cell
Authors: Rana Naba Kumar , Samanta Pijus Kanti
Published: October 2022

Cesium lead bromide (CsPbBr3) Perovskite solar cell (PvSCs) is very popular and a most promising photovoltaic devices with outstanding environmental stability and low-cost fabrication method for commercial application. We have fabricated SnO2 and AZO-based n-i-p PvSCs and compared the power conversion efficiency (PCE) of both the devices. The AZO-based PvSCs exhibits higher value of PCE of 7.30%, with a fill factor (FF) of 63.13%, whereas SnO2-based PvSCs shows 6.17% efficiency with a low FF of 61.55%. Moreover, the unencapsulated device with AZO electron transporting layer (ETL) exhibited remarkable stability in ambient air and retained its 85% of efficiency after 2000 h.
Strong electroweak phase transition in t-channel simplified dark matter models
Authors: Biondini Simone , Schicho Philipp , Tenkanen Tuomas V.I.
Published: October 2022

Beyond the Standard Model physics is required to explain both dark matter and the baryon asymmetry of the universe, the latter possibly generated during a strong first-order electroweak phase transition. While many proposed models tackle these problems independently, it is interesting to inquire whether the same model can explain both. In this context, we link state-of-the-art perturbative assessments of the phase transition thermodynamics with the extraction of the dark matter energy density. These techniques are applied to a next-to-minimal dark matter model containing an inert Majorana fermion that is coupled to Standard Model leptons via a scalar mediator, where the mediator interacts directly with the Higgs boson. For dark matter masses 180 GeV <Mχ≲ 300 GeV, we discern regions of the model parameter space that reproduce the observed dark matter energy density and allow for a first-order phase transition, while evading the most stringent collider constraints.
Non-linear photonic loop mirror based co-site interference canceller
Authors: Chandrasenan Archa , Zacharias Joseph
Published: October 2022

Full duplex-in band (FDIB) is a well-established solution for increasing the data rate and spreading the link range for future communication systems. FDIB systems need no additional bandwidth requirement. However, they are confronted with a major interference challenge on the same site, called co-site interference (CSI). Long-established co-site interference cancellation (CSIC) methods achieve a cancellation depth upto 35 dB, conversely it has space containments, manufacturing imperfections, induces noise penalties and limits isolation bandwidth. To overcome these problems, RF photonic CSIC methods have been developed, which have produced 30 dB wide-band interference suppression. They also increase bandwidth, have a flexible structure, minimize losses and prevent periodic power fading. But these systems have a problem of inherent DC drift, low maintenance of coherence, and low isolation at low transmission power. Thus, there is a high need for photonic CSIC designs of FDIB systems that operate over wider bandwidths and at higher transmission powers. Here, a newfangled CSIC system based on a non-linear photonic loop and frequency down-conversion is proposed. It shows excellent CSIC suppression of greater than 61 dB, for a single frequency signal of interest (SOI) with maximum RF power of 13 dBm. Without frequency down-conversion, the system maintains an average cancellation depth of 62.541 dB for single frequency SOI. After frequency down conversion, the system maintains an average cancellation depth of 61.208 dB for narrow band SOI. The system attains 18% error vector magnitude at −20 dB RF output power, which confirms the comprehensive quality of the system.
Development of a miniaturized, reconnectable, and implantable multichannel connector
Authors: Choi Gwang Jin , Yoo Hyun Ji , Cho YoonKyung , Shim Shinyong , Yun Seunghyeon , Sung Jaehoon , Lim Yoonseob , Jun Sang Beom , Kim Sung June
Published: October 2022

Objective. Connectors for implantable neural prosthetic systems provide several advantages such as simplification of surgery, safe replacement of implanted devices, and modular design of the implant systems. With the rapid advancement of technologies for neural implants, miniaturized multichannel implantable connectors are also required. In this study, we propose a reconnectable and area-efficient multichannel implantable connector. Approach. A female-to-female adapter was fabricated using the thermal-press bonding of micropatterned liquid crystal polymer films. A bump inside the adapter enabled a reliable electrical connection by increasing the contact pressure between the contact pads of the adapter and the inserted cable. After connection, the adapter is enclosed in a metal case sealed with silicone elastomer packing. With different sizes of the packings, leakage current tests were performed under accelerated conditions to determine the optimal design for long-term reliability. Repeated connection tests were performed to verify the durability and reconnectability of the fabricated connector. The connector was implanted in rats, and the leakage currents were monitored to evaluate the stability of the connector in vivo. Main results. The fabricated four- and eight-channel implantable connectors, assembled with the metal cases, had a diameter and length of 6 and 17 mm, respectively. Further, the contact resistances of the four- and eight-channel connectors were 53.2 and 75.2 mΩ, respectively. The electrical contact remained stable during repeated connection tests (50 times). The fabricated connectors with packings having 125%, 137%, and 150% volume ratios to the internal space of the metal case failed after 14, 88, and 14 d, respectively, in a 75 °C saline environment. In animal tests with rats, the connector maintained low leakage current levels for up to 92 d. Significance. An implantable and reconnectable multichannel connector was developed and evaluated. The feasibility of the proposed connector was evaluated in terms of electrical and mechanical characteristics as well as sealing performance. The proposed connector is expected to have potential applications in implantable neural prosthetic systems.
Hybrid mental tasks based human computer interface via integration of pronunciation and motor imagery
Authors: Tong Jigang , Wei Xiaoying , Dong Enzeng , Sun Zhe , Du Shengzhi , Duan Feng
Published: October 2022

Objective. Among the existing active brain–computer interfaces (BCI), the motor imagination (MI) is widely used. To operate the MI BCI effectively, subjects need to carry out trainings on corresponding imagining tasks. Here, we studied how to reduce the discomfort and fatigue of active BCI imaginary tasks and the inability to concentrate on them while improving the accuracy. Approach. This paper proposes a hybrid BCI composed of MI and pronunciation imagination (PI). The electroencephalogram signals of ten subjects are recognized by the adaptive Riemannian distance classification and the improved frequency selective filter-bank Common Spatial Pattern recognition. Main results. The results show that under the new paradigm with the combination of MI and PI, the recognition accuracy is higher than the MI alone. The highest recognition rate of the proposed hybrid system can reach more than 90%. Furthermore, through the subjects’ scoring results of the operation difficulty, it is concluded that the designed hybrid paradigm is more operable than the traditional BCI paradigm. Significance. The separable tasks in the active BCI are limited and the accuracy needs to be improved. The new hybrid paradigm proposed by us improves the accuracy and operability of the active BCI system, providing a new possibility for the research direction of the active BCI.
Fusion by beam ions in a low collisionality, high mirror ratio magnetic mirror
Authors: Egedal J. , Endrizzi D. , Forest C.B. , Fowler T.K.
Published: October 2022

The classical problem of neutral beam ions slowing down in a magnetic mirror geometry is revisited to provide predictive capability for the new Wisconsin HTS Axisymmetric Mirror under development at the University of Wisconsin. A Fokker–Planck model named fast beam ion solver (FBIS) is developed to include the spatial non-uniformity of a physical mirror geometry. The mathematical framework allows for efficient orbit averaging of the pitch-angle scattering operator, and permits a determination of the axial profile of the ambipolar potential confining the electrons. The numerical results from FBIS are consistent with earlier work, but further show how mirror-ratio and a near square magnetic well optimizes the fusion gain. The numerical results are also applied to inform the conceptual design of WHAM++, a low capital-cost breakeven-class magnetic mirror device.
Observation and analysis of lower-hybrid-current-drive density limit in EAST
Authors: Li M.H. , Baek S.G. , Wallace G.M. , Ding B.J. , Wu C.B. , Yan G.H. , Bonoli P.T. , Wang M. , Liu L. , Zhao L.M. , Wu Z.G. , Yang H. , Lin S.Y. , Zang Q. , Yan N. , Zhao H.L. , Huang J. , Zhai X.M. , Li X.X. , Zhang X.J. , Gong X.Z.
Published: October 2022

Lower hybrid current drive (LHCD) experiments with line-averaged density up to ∼5.1 × 1019 m−3 were performed in EAST L-mode plasmas. When the line-averaged density rises above a critical value, the hard x-ray (HXR) emission falls to the noise level, indicating that the LHCD density limit is encountered. The experimental results show that the LHCD density limit can be increased with higher wave source frequency (f
0) and higher magnetic field (B
t). Although a higher LHCD density limit is obtained by a higher magnetic field for both 2.45 GHz and 4.6 GHz waves, the results show a stronger dependence on the magnetic field for the 4.6 GHz case. Analysis suggests that, for normal operation with a relatively low magnetic field (1.6 T ⩽ B
t ⩽ 2.5 T) on EAST, the dominant mechanisms responsible for the LHCD density limit are different between the 2.45 GHz and 4.6 GHz waves. The wave accessibility plays a more significant role during 4.6 GHz LHCD experiments, while parasitic losses due to parametric decay instability (PDIs) dominate the accessibility issue in the 2.45 GHz case. Collisional loss in the scrape-off layer (SOL) may explain the 4.6 GHz result when combined with the accessibility limit at high density and low temperature.
Extension of the energetic particle transport kick model in TRANSP to multiple fast ion species
Authors: Podestà M. , Gorelenkova M. , Teplukhina A.A. , Bonofiglo P.J. , Dumont R. , Keeling D. , Poli F.M. , White R.B. , JET Contributors
Published: October 2022

Alfvénic instabilities (AEs) are well known to cause enhanced transport of energetic particles (EPs) in fusion devices. Most studies until now have focused on characterizing and understanding AE stability in single-species plasmas heated by neutral beams (NB), where deuterium is typically used as both main plasma species and NB fuel. As the fusion community moves toward fusion reactors that target burning plasma conditions, such as ITER, the single-species picture breaks down. Burning plasmas, which will use a mix of deuterium and tritium (DT) as main fuel, also feature the presence of several supra-thermal fusion products such as alpha particles, protons, helium isotopes and high-energy tritium ions. This work presents the extension of the EP transport kick model implemented in the TRANSP time-dependent tokamak transport code to study the combined effect of multiple EP species on AE stability and, in turn, the response of different EP species to plasma instabilities in terms of their redistribution and losses. Further validation of the enhanced model is planned based on experimental results expected from the JET DT campaign scheduled for 2021, in preparation for ITER plasmas and beyond.
TCAD simulation of radiation hard n-MCz and n-Fz Si microstrip detector for the HL-LHC
Authors: Kaur B. , Patyal S. , Saini N. , Chatterjee P. , Srivastava A.K.
Published: October 2022

A radiation hard Si detector is used in the new CMS tracker detector at HL-LHC. It has been observed that n-MCz and n-Fz Si as a material can be used for the Si micro strip detector. The detector design for this material should be simulated and optimized to get high CCE. In order to understand the charge collection behavior of the n-MCz/n-FzSi detector, it is required to simulate and compare the radiation damage effects in the mixed irradiated n-MCz Si and proton irradiated n-Fz Si micro strip detector equipped with metal overhang and multiple guard rings. In this paper, we have done analysis and optimization of the radiation hard n-MCz Si/n-Fz Si strip detector design for the HL-LHC experiment in order to get high CCE.
Role of Artificial Intelligence in improving structural performance: A Review
Authors: Shandilya Tanmay , Agrawal Vinay , Gupta Rajesh
Published: October 2022

Artificial Intelligence, or AI, encloses within itself, the various techniques and algorithms that facilitate the augmentation of human decision-making by adding computational infrastructure to it. It includes specific methodologies and programs that help make conclusive deductions based on the data available for it to work. The paper attempts to provide an introduction to the different types of AI tools along with their applicability. Furthermore, it attempts to define the role of AI in the enhancement of structural performance. Civil Engineering is a discipline that is highly dependent on the judgement of the Engineer-on-field. AI can assist this judgement by providing meaningful insights on the real world problems based on the data available from the site thereby improving the quality of the work and simultaneously serve as a guideline for novice engineers. This paper highlights the significance of AI in different domains of Civil Engineering and provides a broad picture of the future possibilities. It provides a review of the prominent works that have been carried out in the area and segregates the researches needing immediate attention. The areas of focus include structural performance parameters including prediction of structural properties, structural health monitoring and infrastructure-specific issues in buildings and bridges.
Life Cycle Cost Analysis of rooftop gardens using openLCA
Authors: Dhivya Barathi R , Vidjeapriya R
Published: October 2022

Most innovative and eco-friendly project alternatives are rejected due to higher initial costs. This problem arises due to the general cost analysis that considers only the initial costs. It can be solved using Life Cycle Cost Analysis (LCCA) approach because LCCA helps the decision makers to select the project alternative with more economic benefits by considering the costs incurred in it throughout the life cycle. In this paper, the life cycle cost analysis of the rooftop garden was carried out and compared with the conventional roof using openLCA software. The rooftop garden includes many environmental benefits such as the reduction of the urban heat island effect, reduction of noise pollution, improvement in quality of air, management of surface runoff and conservation of biodiversity. Still, the use of rooftop gardens is not common in the projects due to their higher initial costs. Thus, LCCA was carried out to evaluate its economic feasibility. A model was developed using openLCA software to carry out the analysis. The costs considered in the analysis include the initial costs, maintenance costs, renovation costs and energy costs. The cost data were collected for extensive rooftop gardens laid in commercial buildings in and around Chennai city. The results indicate that the initial cost of the rooftop garden was 5.2 times higher than that of the conventional roof but due to the prolonged life period and the energy savings of the rooftop garden, the life cycle cost was 5.25% lower than that of the conventional roof.
Optimum Orientation of Geofoam Inclusion in the Retaining Wall
Authors: Premanvitha P , Sravanam Sasanka Mouli
Published: October 2022

Expanded polystyrene (EPS) geofoam is one of the lightweight materials used in civil engineering applications. Present study deals with the application of geofoam in the retaining wall as a backfill. In this study, two-dimensional finite element software is used to simulate a retaining wall with geofoam. A wall of 6m height is considered. Lateral pressures and surface settlements are examined for various orientations of geofoam. Orientations include upper triangular, lower triangular, and rectangular patterns. The results are generalized for various wall heights. Placement of geofoam in rectangular pattern is found to lead the least lateral pressure.
Accident analysis and road safety audit: a case study on NH-76
Authors: Izharul Haque Md , Khan Amir Ali , Singh Gyanendra , Dass Sachin , Jaglan Saurabh
Published: October 2022

Road accidents in India are on the rise as the country’s vehicle population grows. As a result, a considerable number of lives and assets have been lost. The formal process for determining causal factors responsible for road accidents in new or improvement of existing road projects without any major modification in the design is known as a road safety audit. This study examines the traffic safety situation on NH-76 from Udaipur to Chittorgarh in the state of Rajasthan, India, intending to identify causal factors responsible for road accidents so that the real damage resulting from road collisions can be reduced to some extent in the future. For this study, a 93.5-kilometer span was chosen and accident data was obtained from the enforcement department via recorded accident FIRs from 2017 to 2019. The accident data was studied to determine the reasons, taking into account yearly, hourly, time-wise, day-wise variation, accident nature-wise, and other factors. Black spots were also identified in the study area and recommendations based on analysis were made to prevent traffic accidents and make the route safer for users. The purpose of this study is to uncover flaws, improve design characteristics, and improve road credibility.
A Study on Road Safety Audit and Black Spot Identification
Authors: Nuli Sadguna , Rohan Katkam , Joshnavi Chenreddy
Published: October 2022

Road Safety Audit (RSA) is a formal procedure for assessing accident potential and safety performance of new and existing roads. Road safety audit is an efficient, cost effective and proactive approach to improve road safety. It is proved that RSA has the potential to save lives. The RSA was originated in Great Britain and is well developed in countries like UK, USA, Australia, New Zealand, Denmark, Canada, Malaysia and Singapore. Presently, it is at varying stages of implementation in developing nations like India, South Africa, Thailand and Bangladesh. Therefore, road safety audit appears to be an ideal tool for improving road safety in India. In this study, a rural road stretching from Rallaguda bridge to Vardhaman College of Engineering in Hyderabad city is chosen for road safety audit. Safety assessment is done using iRAP application by collecting road side features, midblock details, intersection features, vulnerable road users’ facilities, speed and flow details. The secondary objective is to find out the Black Spot locations within Rajiv Gandhi International Airport (RGIA) police station jurisdiction of Hyderabad city. Accident prone areas are identified by estimating Weighted severity and accident severity indices with the help of historical accident data. Finally, major causes of accidents and measures to improve safety of the chosen road section are suggested.
Real-Time Traffic Prediction Using Neural Networks
Authors: Nuli Sadguna , Vikranth Nagula , Gupta Kothuri Avinash
Published: October 2022

Somewhat recently, the issue of traffic has become more extreme because of industrialization particularly in significant urban communities. A higher standard of living in cities is pushing people to utilise their own vehicles instead of public transportation. Thus, there is tremendous increase in traffic, which leads to a variety of other associated issues. In order to get from one place to another, one must spend more time travelling than they would have otherwise, which also raises the fuel consumption. The traffic data that is gathered by various detectors is highly dynamic and non-stationary. For example, the number of vehicles turning at an intersection cannot be stated with greater accuracy. Consequently, it is challenging to develop a mathematical model to determine green time. However, the introduction of Intelligent Transportation Systems (ITS) in modern times enables the detection of traffic events, communication, information processing, and user action. One of the most crucial criteria for this system to work successfully is the ability to precisely predict the pattern of the traffic stream. In order to predict future traffic flow, a system that uses artificial neural networks and real-time traffic data was proposed in this study. Neural networks have the ability to predict the future by learning from the past. Specifically, this study predict traffic volume in two levels such as short-term for every 15 minutes interval and mid-term for every one hour of a given day. These predictions help in dynamic traffic management applications like signal control, congestion management, and travel time predictions etc.
Flood Forecasting Using Artificial Neural Network
Authors: Mistry Shivangi , Parekh Falguni
Published: October 2022

The process of assessing the timing, amount, and period of flood events based on observed features of a river basin is known as flood forecasting. Floods cause lots of damage to properties and create a risk to human life. Flood forecasting is critical for developing appropriate flood risk management strategies, reducing flood hazards, evacuating people from flood-prone areas. The main objective of this study is to apply artificial neural networks for forecasting of river flow in the Deo River, located in Gujarat. Rainfall and discharge are the parameters considered for model development. The developed model is validated to test the accuracy of the model. Trained and validated models are evaluated using performance indices. Six alternative flood prediction models have been developed using ANN. These models are developed based on various training algorithms. A single layer feed forward back-propagation neural network with six different training algorithms (Scaled conjugate gradient, Levenberg Marquardt, Resilient back-propagation, Conjugate gradient, and Cascade forward back propagation, Bayesian regularization) was developed, with 70% of the data used for training and 30% for validation. The created models’ performance is assessed using statistical performance parameters. The best performance was obtained with an ANN model developed using the Cascade forward back-propagation training algorithm, which had a coefficient of correlation (r) of 0.83, a coefficient of determination (R2) of 0.70, and a root mean squared error (RMSE) of 5.58 for training and a coefficient of correlation (r) of 0.89, a coefficient of determination (R2) of 0.70, and a root mean squared error (RMSE) of 7.27 for validation. The forecast inflow is very close to the observed values. This study shows that ANN can be used to successfully predict floods, and the model developed can be used by flood control departments across the country for flood forecasting.
Coconut shell derived coal as low-cost adsorbent for the fluoride removal from drinking water
Authors: Bhamare Pratik , Bagul Tushar , More Ashok , Gadekar Mahesh
Published: October 2022

Fluoride in drinking water pose several health issues such as fluorosis, thyroid problems, neurological problems and fluoride poisoning. Amongst several approaches adsorption is one of a better low-cost technique. Present study focused on the use of granular coal made up of coconut shell as adsorbent for the fluoride removal from drinking water. The batch adsorption study conducted to study effect of fluoride concentration (2-10 mg/L), adsorbent dosage (2-10 g/L), pH (4-8), and contact time (0-120 min) on adsorption performance. Maximum adsorption of 1.37 mg/g was observed at pH of 5.9, adsorbent dose of 2 g/L, at 60 min of contact time. Furthermore, the data was fitted in Langmuir and Freundlich model and also modelled in the Artificial Neural Network (ANN). ANN shows a better modelling with coefficient of correlation about 98% and close to zero mean square error. The study indicates that coconut shell’s coal easy to prepare at rural locations and would be a low-cost adsorbent.
Film thickness in miniature ball bearing grease lubricated
Authors: Cojocaru D , Ianuş G , Cârlescu V
Published: October 2022

In this paper the authors theoretically evaluated the film thickness in a miniature angular contact ball bearing in grease and oil lubricated conditions and correlated with the variation of the electrical resistance experimentally determined by using tribometer CETR UMT-2. For grease the authors determined the film thickness considering base oil viscosity. The rotational speed of the inner race varied between 1 and 500 rpm and the axial load applied on a 7000C angular contact ball bearing was 8.1 N. The IVR and EHD lubrication regimes were analytically evaluated depending on the rotational speed and lubricants for both inner and outer race. Based of the dependence between film thickness and electrical resistance obtained for oil was evaluated the real film thickness obtained by using the grease. In case of oil lubricated condition, the experimental results showed an increase of electrical resistance with the rotational speed caused by increasing of the film thickness according to the theoretical model. For grease lubricated condition, ”a V-shaped pattern” was obtained. High values of electrical resistance at very low rotational speeds were observed. By increasing the rotational speed the electrical resistance for grease decreases until a limit speed and increase continuum over this limit. This behaviour was also reported in literature by ball-disc interferometry that showed at very low speeds that the thickener is dominant and over a speed limit the base oil is dominant in generating the film thickness.
A simple method to introduce the centrifugal effects in an angular contact ball bearing
Authors: Zamă A , Tufescu A
Published: October 2022

An analytical model was developed for angular contact ball bearings running at high speeds. The model presented in this paper was designed for the 7206 C angular contact ball bearings and considers the geometrical parameters as well as the interactions between the raceways and the rolling elements involved while bearings are in operation. Using an original methodology, the effects of centrifugal forces generated by the rolling elements have been evidenced both on the normal contact load distribution and contact angles between balls and the two races. The effect of centrifugal forces was considered as a “supplementary clearance” included in a general model developed by Houpert for static conditions. Some simulations for various axial and radial loads and high rotational speeds have been presented. The results confirm important deviations of the static contact angle and the load distribution on both races.
Mechanical and structural characterisation of a 3D warp-knitted spacer fabric subjected to compression
Authors: Lupu G C , Fătu A , Henry Y , Turtoi P , Cicone T
Published: October 2022

3D warp-knitted spacer fabrics show a growing importance, especially in cushioning or impact damping applications. The use of 3D fabrics saturated with fluids improves their impact damping capabilities and, in this case, evaluating the variation of material’s permeability with compression level is of great importance. In the past few years, our efforts were focused on evaluating this variation with the use of complex experimental devices, an approach that has proven to be very useful and thoroughly, but also time and resource consuming. Through this new initiative we aim to make a step further in our attempt to model the behaviour of dry or imbibed 3D warp-knitted spacer fabrics by considering their complex internal structure. A 3D model was built, based on a CT scan of a commercially available 3D fabric, which allowed us to simulate using the finite element method the structure’s response to different compression levels and conditions.
Equipment for thermo-mechanical contact fatigue in rolling conditions determination
Authors: Mistreanu S , Tudose-Sandu-Ville F , Manole V , Ştirbu I
Published: October 2022

The paper refers to the influence of corrosion on the installation and development of thermos - mechanical contact fatigue on metallic elements. The analysis takes into account the influence of the thermal Jacq effect on the position of the origin of a crack following the thermos - mechanical contact fatigue. Here are presents some aspects concerning mechanical contact fatigue and corrosion wear and the links of these two kinds of wear in the common deterioration of the contact layer. Schematic draw of the test stand is presented with the main component elements and thermal anomaly effect Jacq in heat conduction was analyzed. To validate the theoretical aspects presented, a test rig is introduced and an experimental program of testing is developed.
Eddy current assessment of flaw severity of cylindrical products
Authors: Savin A , Steigmann R , Iftimie N , Dobrescu G S , Craus M L
Published: October 2022

This paper proposes the use of specific procedures of electromagnetic nondestructive testing method for evaluation of flaw severity in cylindrical products. The phenomena of mechanical and / or thermal fatigue as well as accidental handling can generate the appearance of flaws followed by the increase of these in the metal tubes. This paper proposes the use of specific procedures of electromagnetic nondestructive testing method for evaluation of flaw severity in cylindrical products, which included in a database, makes it useful for the operation of automatic classification of the severity of discontinuities, being based on the method of neural network “learning” to remain immune to certain signal-to-noise ratio. With this, inner circumferential discontinuities with 1mm depth can be detected with probability of detection more than 89% for 90% confidence level.
Design and simulation of an Unmanned Aerial Vehicle based on a motor glider concept
Authors: Pop S , Steopan A , Luculescu M C , Boer A L , Cristea L , Zamfira C S
Published: October 2022

Due to the miniaturization of optoelectronic devices, the increase in computing power, and the improvement of control systems and navigation systems, Unmanned Aerial Vehicles (UAVs) have become an indispensable tool in areas such as agriculture, industry (critical infrastructure inspection), and surveying. These systems are available in fixed-wing and rotary-wing (multiple rotors) configurations. The multiple rotor system is characterized by advantages such as vertical take-off and landing and simplicity of the structure design and control algorithm. Still, there are also disadvantages: the short flight time and very high energy consumption. Based on the requirement for a platform with high reliability and high flight range, the paper proposes a solution for fixed-wing UAVs with an extended flight time, self-launching, short landing, and optimized energy consumption. The presented solution is inspired by the model of the Romanian glider IS-28B2 produced by ICA Ghimbav, which has been redesigned and optimized to become a 1:10 scale UAV type glider. The paper presents the 3D model design, simulation, and optimal autopilot integration for this robotic aerial system.
Analysis of thin wall cells made of Zhermack silicone rubber used for lower limb prosthesis
Authors: Spanu Alina Rodica , Besnea Daniel , Moraru Edgar
Published: October 2022

The suspension system of the lower limb prosthesis has the main role of providing the permanent contact with the stump. The paper proposed the FEM analysis and the experimental study on the thin wall cells as part of a network inflated with dry air at very well controlled pressure values. The cells are made of bicomponent silicone rubber Zhermack that is biocompatible and has very good elastic properties. The theoretical aspect of this study by using FEM method has computed acceptable values for the Von Misses stress and for the deformation, so that the pressure over the tissue is inside the recommended limits. The designed experimental set-up provides the values for pressure force needed to keep the permanent contact over the entire external surface of the thin wall cell.
Proposed gear rack cutter for spur gear manufacturing by generating method. Part II: Comparison between the standard and modified profiles
Authors: Alaci S , Ciornei F-C , Doroftei I A
Published: October 2022

The paper proposes a method of cutting by generating of spur gears using a rack cutter with a modified geometry. The analytical equations of the tooth profile of the modified rack-gear cutter are deduced, both for involute zone and for filleting region, based on the remark that the profile is the envelope of successive positions of the tool. The undercutting radius for the modified profile is obtained from a system of transcendental equations which requires and a numerical method for solving it. Compared to the standard profile, the differences are insignificant. A program was written and the profiles of the teeth are represented for two shifting coefficients, for the standard and the modified tooth profiles.
Dimensional synthesis and comparative simulation of two planar deployable mechanisms
Authors: Doroftei I , Doroftei I A
Published: October 2022

Deployable structures have the ability to change their shape and volume, being used to design mobile structures with various applications in architecture. Planar or spatial mechanisms with articulated bars, folding plates or membranes could be used to realize such structures. In this paper, dimensional synthesis and simulation of two deployable structures based on a modified scissor mechanism will be presented.
Vickers Hardness Variation on the Part and Welding Cord Subjected to Plastic Deformation
Authors: Goanta V , Moraras C I
Published: October 2022

By performing Vickers identifications in the area of the weld bead and the areas adjacent to it, the degree of plastic deformation can be assessed, highlighting the different hardness in the case of welding and the base material. During this work, welded specimens were made in the central area with a double V-shaped cord. One of the specimens was loading until breaking, noting that the rupture occurred in an area further away from the welding area. Another 13 specimens were required at varying degrees of deformation. Stresses above the elastic limit create differences in the plastic deformation of the areas of the weld bead and those in its vicinity. Due to the fact that the base material and the material of the weld bead have different elastic characteristics, much more pronounced plastic deformations occur in the base material compared to the weld bead. It was found that the base material suffered significantly greater plastic deformation than the weld bead. Significant differences in hardness occur in the area of the weld bead relative to the area of the base material.
Acoustic and elastic properties of wood used for musical instruments
Authors: Stanciu M D , Gall R , Orbok Z , Stan T
Published: October 2022

This paper proposes an ultrasound method for determining the elastic properties of anisotropic orthotropic materials used stringed instruments (in our case violins) manufacturing. Samples from different wood species were subjected to the propagation of the ultrasonic wave front, the signal being received through a receiver. The sensors were placed successively on the three main orthogonal directions of the wood, obtaining the values of the ultrasound velocity in different directions. Subsequently, based on the mathematical relations, the values of elastic parameters were calculated.
An Overview of Actual Braking Systems
Authors: Boitan E M , Ulian T M
Published: October 2022

Braking systems are undergoing major changes to meet new safety and environmental requirements. As a safety component, the braking system is capable of assisting the driver or intervening autonomously when the stability of the car compromised, or when the driver wants to avoid collisions or limit the consequences of an accident by reducing relative speed at impact. With the brake system actions, the goal of reducing road fatalities is being achieved, and this cannot be without reducing human error as well. New brake-by-wire systems were developed in the automotive industry to improve strategies such as traction control. These systems provide distributed braking forces, regenerative braking, and traction control. It combines electronic, mechanical and hydraulic components and is constantly evolving since human beings are concerned with safety and performance.
Experimental methods to investigate the performance of the braking system using GPS and IMU equipment
Authors: Drosescu R , Cojocaru D , Zamfir S
Published: October 2022

Establishing procedures and equipment for more accurate evaluation of the brake system performances is a major goal for automakers, but also for researchers, test equipment manufacturers, racing drivers and their staff, or for experts and forensics in their activity of accidents reconstruction. Increasing the performance and complexity of new vehicle stability control systems as well as driver assistance systems require finding new solutions for measuring and determining braking and stopping time and space, as well as a lot of new parameters such as braking system response, driver’s reaction times, actual value of the traction grip, corrections due to the slope of the road, or to the differences between the actual speed and the one displayed on board. Changes in adhesion and normal load on each wheel contact patch that occur under certain driving conditions develop lateral forces and yaw that disrupt longitudinal dynamics and must be determined and considered. The lack of braking marks in the case of partially braked or unlocked wheel by the ABS system is also a major impediment to the correct and accurate reconstitution of the braking and stopping space or speed. This paper describes a series of experimental research carried out by the authors using a professional GPS device, IMU, infrared thermal camera and a series of sensors that allow to determine with high precision the trajectory, radius of road curvature and tilt, the vehicle real speed, longitudinal and lateral accelerations, yaw speed or drift angle. Based on these determinations, several braking and acceleration parameters were estimated in alignment, in curves or in ramp and slope, respectively in coast down mode.
Cold flow simulation for a S.I. engine with shrouded intake valve
Authors: Fratita M , Rusu E
Published: October 2022

The aim of the work is to analyse the impact of the intake valve design on the cold flow of internal combustion engines. Two shrouded intake valves and one basic intake valve were used for the analysis. Tests have been carried out for a wide range of speeds. The two models of shrouded valves use different concepts, and to increase swirl and tumble turbulence respectively. The results of the simulation show a clear increase in turbulence, sometimes at the cost of decreasing the volume efficiency.
Design and finite element analysis of a circular steel profile frame using Autodesk Inventor
Authors: Popescu F , Chivu R M , Uzuneanu K , Ion I
Published: October 2022

The paper aims to apply the technical knowledge of recreational vehicles and the skills of using CAD applications for the design and construction of a steel profile frame. After the synthesis of the specific theoretical elements, from the specialized literature, the paper explores subassemblies of a kart, for which it proposes modeling studies. One element under analysis is the go-kart chassis. Designed in two constructive variants, the chassis is investigated in terms of rigidity, using finite element analysis specific to the Autodesk Inventor Professional application. The obtained results and the additional calculation elements, regarding the dynamics of the designed minivehicle, allow the physical realization of a chassis with increased rigidity.