bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of mechanical characteristics of 3003 aluminum alloy plated sheets
Authors: Lazar (Natra) C , Istrate D , Odagiu O P , Demian A M , Buzatu A D , Ghiban B
Published: October 2022

Aluminum based alloys are widely used as applications for heat exchangers, especially for car radiators. The main alloy used is 3003 (in according with ISO6361), which is usually plated with a 4000 series alloy (which has a lower melting point). The present paper gives a comparative analysis of the mechanical characteristics values of the 3003 alloy plated sheets, in different states (state O and state H24), and different sheet thicknesses (0.5 mm, 0.97 mm, and 2 mm respectively). Statistical comparative analysis shows that the considered processes are stable (in control) in the sense of control chart (X chart and R chart values) are within the control limits and there are no specific trends. The stability of the processes was highlighted by the use of performance indices. Thus, the CPK performance index in all the analyzed situations is much higher than 1.33, which means that the processes are stable with a normal distribution of values. Instead, the PPK capability index values are much lower than CPK. The distribution of elongation values (in state O, at a thickness of 0.97 mm - with the value of the PPK capability index 1.95 and in state O 2.5 mm thickness - with the value of the PPK capacity index 2.25 mm) has a value greater than 1.67, which indicates that this characteristic is in a state of statistical control (ie PPK ≥ 1.67 and CPK ≥ 1.33). The fact that for the other characteristics the value of the PPK ≤ 1.67 capability index, and yet the process is stable, means that there must be process improvements through various corrective measures until continuous stability is achieved. The complete statistical analysis, performed on the values of the mechanical characteristics, of the 3003 alloy plated sheets, in different delivery states and different thicknesses, showed, finally, that the applied technological processes led to obtaining appropriate mechanical characteristics, without deviating from outside the limits of tolerance, with high reproducibility and stability.
Structural analysis and mechanical properties of some coatings obtained by cold spray method. A review
Authors: Lupu F C , Munteanu C , Istrate B , Lupescu S C , Ciubotaru R , Adrian S
Published: October 2022

In this paper a documentation was made to highlight the characteristics obtained on surface modifications by means of the Cold Spray, using different powders based on tungsten carbide (WC) and agglomerated with nickel, sprayed on different materials, as well as the possibility of using 52100 steel, which is often used in the manufacture of rolling bearings and which has acquired high performances both in terms of wear and fatigue and in terms of high resistance due to the alloying with chromium and the high percentage of carbon. Studies on the use of WIP-C1 powders, powders attributed exclusively to the cold spraying process, and the prior use of WIP-BC1 powders, intended to establish a stronger bond between the substrate and the base layer, have shown that good wear and impact resistance is obtained and the risk of delamination and interfacial porosity has been minimised. Studies with different coating compositions using several methods to improve surface quality by surface spraying, namely HVOF (high velocity oxygen fuel), CGDS (cold gas dynamic sterilization) and CS (cold spray), led to an improvement in performance, with the cold spray process showing improved scratch resistance, good adhesion between the substrate and the sprayed layer and higher hardness. Surface spraying is an efficient process to obtain additional characteristics, improving mechanical, tribological, corrosion and erosion properties, and of all the other techniques, Cold Spray becomes competitive because it is the only technology that deposits particles below the melting point.
Biomechanical properties of animals bones and the influence of oncologic drug on pig femur
Authors: Rosca J C Mirza , Suárez N R. Florido , Baltes L , Tierean M
Published: October 2022

Over the years, we have seen how, thanks to experimentation on animal models, the foundations have been laid in the field of implantology. In most cases, studies related to the bone scale are carried out on the species that are most similar in their movements and behavior to humans. The femur has been selected as the reference bone for our test, selecting as animals to experiment with the goat breed, the bovine breed and the porcine breed for their similarity to the human body, obtaining specimens of the cortical part of the bone. Destructive bending tests will be carried out in the same way on each of the femur fragments of each animal. When interpreting the results, we will be guided by taking sections of the transverse and longitudinal part of the bone, performing the tests in both cases inside the femur, and once the results have been obtained, we will proceed to their subsequent evaluation. We relate the bone resistance of the samples to the effect of an oncological drug, Altan Zolendronic Acid 4 mg/ 100 ml solution for perfusion EFG, administered in cases of bone metastasis.
An Example for Determining the Physical Parameters Used in DEM Modelling for the Interaction Process between Aggregates and Working Equipment
Authors: Niţă A , Laudacescu E , Ramadan I N , Petrescu M G
Published: October 2022

Modern economies are based on an efficient communications and transport infrastructure. In this context, road networks make an essential contribution to the movement of large quantities of raw materials, finished products as well as to human transport for productive or recreational purposes. In order to maintain the optimal functioning of the road infrastructure, it is necessary to ensure high quality lanes. Road construction and maintenance work play an important role in supporting the ideas mentioned above. The used equipment for production of asphalt pavements (asphalt concrete) and their maintenance are the subject of numerous studies, proving the interest for this field. The authors of paper: An Example for Determining the Physical Parameters Used in DEM (Discrete Element Method) Modelling for the Interaction Process between Aggregates and Working Equipment, present an example for determining physical parameters that are used in specific numerical modelling of operation equipment which interacts with structures (drum dryer, mixer for concrete production and milling machine for asphalt pavement). In order to model the real phenomena in which granular materials are involved (cereals, mineral aggregates, and other powdery substances) it is very important to use not only appropriate software but also to use primary data to accurately characterize the phenomena. The sizes that characterize the interaction between particles and between particles and the space in which they move are very important. The study covers any type of granular material of mineral origin, in particular mineral aggregates used in the manufacture of concrete, cement or asphalt.
Design recommendation for thermal conductive plastic parts in automotive industry
Authors: Pal S G , Bistriceanu D P , Vornicu V
Published: October 2022

In this paper we will present a mechanical study made on the design of thermal conductive plastic parts. Out of our study derived new design rules that are useful for mechanical design engineers that have to create parts built from this type of materials. We used Catia V6 software for modelling the parts and ANSYS Moldflow software to simulate the behaviour of real components. The solutions resulted from our trials are improving the quality of the parts built from thermal conductive plastics. The test and simulation results lead us to new rules for designing screw domes and rivets for thermal conductive plastic parts and reducing warpage effect with 75% on this kind of parts.
LabVIEW Instruments for Creating Brain-Computer Interface Applications by Simulating Graphical Animations and Sending Text Messages to Virtual and Physical LEDs Based Display Systems Connected to Arduino Board
Authors: Ruşanu O A
Published: October 2022

The brain-computer interface (BCI) is a multidisciplinary research field aimed at helping people with neuromotor disabilities. A BCI system enables the control of mechatronic devices by using cognitive intentions translated into electroencephalographic signals. This paper presents the implementation of LabVIEW-based display systems that can be controlled by a brain-computer interface based on detecting the voluntary eye blinks used as commands. The interactive virtual or physical display systems are helpful thanks to running or simulating various graphical animations or transmitting different text messages in a user-customizable way. The proposed LabVIEW-based virtual display systems provide versatile functionalities such as: customizing the own visual animations and the movement of any text message by switching the direction (to the left or to the right) depending on the user’s choice. This paper presents five original virtual LEDs based display systems developed in LabVIEW graphical programming environment. The implemented LabVIEW applications included: an 8x8 LEDs matrix for simulating graphical animations, 2x16 LCD TEXT for showing text messages, and a 7-segments display for implementing chronometer functionality. Moreover, the LabVIEW virtual display systems were interfaced with the physical display systems (8x8 LEDs matrix controlled by MAX7219 driver and 2x16 LCD TEXT) connected to the Arduino Uno board.
Some analyzes on box girders bridges - literature review
Authors: Velniciuc A M , Bujoreanu C
Published: October 2022

Studies on box girders bridges that treats domains such as: its seismic response, fire resistance of the structure, effect of web inclination of the bridge, shear force distribution in webs of the bridge, loading conditions for the bridge with dead load and live load were reviewed and concluded. Our paper aims to describe different research from the dedicated literature using software such as Ansys, Midas, CSi Bridge with FEM (finite element method) and to highlight the points where the maximum stress values are found. This will help us in the future to compare these results obtained by experts with new analyzes that we want to accomplish regarding the efficacy and reliability of the box girder structure. The main motivation to study this domain is represented by the previous experience and knowledge and to detect new dangerous sections in this type of structure. By counteracting the dangerous sections, we can improve the reliability degree and efficiency of the box girder bridge structure.
The structural groups approach and transmission angles limits
Authors: Duca C D , Buium F
Published: October 2022

Present work makes a synthesis of a papers cycle in which it were shown a new approach to appreciate forces transmission in mechanisms and so, we performed the structural groups procedure. This approach makes forces transmission analysis for each structural group, not for the mechanism taken as a whole. This point of view enables approach of every mechanism used into practice, as we have shown in third section. Besides this, the proposed procedure clarifies some problems, like those regarding mechanisms containing RTR structural group.
Numerical investigation of the stress state in the runner hub of a Kaplan turbine
Authors: Cojocaru V , Miclosina C-O , Campian C V , Frunzaverde D , Nedelcu D
Published: October 2022

In the context of global warming, Romania has assumed through European directives to increase the percentage of energy produced from renewable sources. In the last years, energy generated in hydropower plants had the largest contribution to the total renewable energy production. This is expected to continue in the forthcoming period, considering the seasonal nature of energy produced in photovoltaic and wind farms. Therefore, efforts are made to increase the installed power of hydropower plants and to reduce the downtime for maintenance and repairs. Increasing the installed power requires an accurate diagnosis of the components of hydro turbines. In Kaplan turbines one of the main components is the runner hub. The runner hub is subjected to a complex state of loading that depends on several factors, the most important being the runner opening and the operating mode. This paper presents a methodology for numerical analysis of the stress state of a six-bladed Kaplan runner hub. The algorithm for transposing to the hub the forces that act on the runner (hydrodynamic loads, mass and inertial forces, forces generated by the action of the servomotor) is described. The results of the numerical analysis are presented in the form of stress and displacement plots.
Calibrating a double aluminium bar with electrotensometric strain gauge attached
Authors: Dontu A I
Published: October 2022

The transducers which are used for measuring force or weight are also called load cells. Most of those transducers use strain gauges to measure the applied force. In this paper, a calibration of a double aluminium bar with strain gauges attached is conducted in order to determine the major sources of error in the measurement process. The authors explain the entire process of calibration for a single load cell. The purpose is to determine the main measurement errors. The sensor was calibrated at maximum of 10 kg and loading were made by manual application of weights. The results of calibration reveal a very small hysteresis and linearity error which makes the sensor a reliable choice to measure force, weight, or load.
Static calibration of a modified weigh-in-motion sensor
Authors: Mihaila M , Blanari I , Barsanescu P D
Published: October 2022

This paper presents the calibration in the laboratory of a weigh-in-motion sensor. The sensor has the shape and external dimensions of a bump speed and is mounted on the road as well. The sensor was designed using finite element analysis (FEA) and Computer Aid Design (CAD) programs. The sensor was made of sheet steel and its components were welded together. Strain gauges were mounted on the elastic element. A FEA simulation of the static calibration operation was performed. The sensor was then installed on an Instron 8801 testing machine and static compression calibration was performed. The results of the calibration are presented in this paper.
Finite element analysis of a modified weigh-in-motion sensor
Authors: Mihaila M , Blanari I , Goanta V , Barsanescu P D
Published: October 2022

The weigh-in-motion (WIM) sensors can measure the weight on each wheel, on the axle and thus can then determine the weight of the entire vehicle. These sensors are also used for traffic monitoring, both in volume (number of vehicles) and structure (classification by vehicle type). This paper presents the finite element analysis (FEA) of a sensor for urban traffic, which is carried out at medium speeds (around 50km / h). The sensor has the shape and dimensions of a speed bump and is mounted on the road in the same way. With FEA, the state of stress, strain and displacement in the elastic element of the sensor were determined, as well as the contact pressures between the tire and the sensor. For FEA different types of vehicles (a car and a truck) were considered which cross the sensor in the central area or in the side areas.
Structural evaluation of a pusher-tug vessel to comply with the requirements for navigation in ice covered waters
Authors: Moise L A , Pohilca A M , Mocanu C I , Domnisoru L
Published: October 2022

The design of a standalone ice breaker vessel destined for inland navigation could be a costly solution for a temporary problem, due to the limited period of time when the vessel is engaged in ice breaking operations. The Romanian Authorities have in their possession a dedicated ice breaker, Perseus, destinated to clear the navigation path on the Maritime Danube River but which cannot navigate upstream on the Fluvial Danube River due to its draft limitations. As a consequence, most vessels trading from Braila and upstream are exposed to high risks due to the possibility of being trapped in ice formations that could be dangerous for both for the crew and vessels during the winter season. A viable solution is represented by designing a removable ice breaker module that could be attached to the existing fleet of pusher vessels. Since it is not a stand-alone vessel, it will not require a dedicated crew onboard and will only operate when ice dams are created along the river and the navigation path needs to be cleared. The existing fleet of pusher vessels is not prepared to navigate in ice covered water and thus structural reinforcement are required to comply with the requirements provided by classification society. The current paper presents the evaluation of the existing structure of a pusher vessel and proposes means of reinforcement to comply with ICE B class notation provided by DNV Class Society. The paper will conclude on the definition of the ice belt area (LIWL, UIWL) along the ship’s side and will provide scantling information for the new structure within the ice belt area.
Laboratory scale technology for a ballistic protection panel and preliminary results
Authors: Ojoc G G , Deleanu L
Published: October 2022

This paper presents a laboratory scale technology for manufacturing a composite with ballistic protection characteristics for a certain level of threat. The composite is made of quadriaxial fabrics, with four oriented substrates (0°/+45°/90°/-45°), which assumes from the start that the fabric will have a quasi-isotropic behavior. The selected resin to bind the layers is made of two-component resin Biresin® CR82, with hardener CH80-2 (supplied by Sika Group). This technology implies cutting, a laying-up process, a maintenance in press, under load, for at least 8 hours, a natural aging during 7 days, and a heat treatment, in two stages, taking into account the software of the used oven, of 3 hours each, at 60 °C. There were manufactured sets of 8-layer panels and 16-layer panels, checking to have a narrow tolerance of the thickness for the set of panels with the same number of layers. The process has repeatability, precision and robustness. The recipe for making panels and the laboratory technology are original. The manufacturing process was made in compliance with the norms of safety and health at work, with adequate protective equipment. The test campaign aimed to evaluate the behavior of ballistic protection panels, at the action of bullets of 9 mm FMJ, by firing in a specialized laboratory, the method being the one recommended in the standard EN 1522/2004. The bullet has the average initial speed of 373 m/s, at a distance of 5 m (normal conditions). Only the dimensions of the test samples, which were 300 mm x 300 mm, are smaller than those required by the standard (500 mm x 500 mm). The obtained results and the mechanisms of target failure (at full penetration for 8-layer panels and partial penetration for 16-layer panels) are discussed in order to improve the response of the target, by changing parameters, such as the number of layers of the panel, that influenced weight.
Automatically collecting data traffic in intersections by using video analytics software for vehicle counting
Authors: Dontu A I , Gaiginschi L , Sachelarie A
Published: October 2022

Traffic volume and composition data are important for infrastructure planning and increase traffic safety. The actual survey techniques depend on the goals of the survey, the amount of traffic data and the human and financial resources available. The purpose of this research is to improve classical collecting data by creating an automatically collecting data traffic with the help of a video analytics software. Authors present in this paper a new method for automatically collecting data traffic using Camlytics, a video analytics software, which is automatic processing the videos. This method is less time consuming, don’t need a significant human resource and it is easy to apply. Also, this new method for counting the traffic may be used by the municipality for making a better fluidisation of traffic in the city by corelating the data traffic with the Intelligent Transportation Systems (I.T.S.).
Cold flow simulation for an Internal Combustion Engine with swirl flaps
Authors: Fratita M , Rusu E , Burciu S M
Published: October 2022

The paper aims at CFD analysis of engine cold flow when swirl flaps are used. The CFD analysis was performed using a RANS-RNG turbulence model to predict the evolution of engine cold flow at different engine speeds for two operating conditions with swirl flaps and without swirl flaps. The results show that swirl flaps can increase the average turbulent kinetic energy by up to 30% for a speed range of 1000 - 2000 rpm. However, over 3000rpm swirl flaps will worsen volumetric efficiency due to the change in the cross section of fluid flow to the cylinder.
Analytical model for the frontal impact with a non-deformable barrier
Authors: Manea A M , Iozsa D , Molea A , Stan C
Published: October 2022

According to the literature, a relatively simple models have been developed, capable of simulating the front compartment (FC) integrity during a frontal impact (FI) of a vehicle. These models, known as the Lumped Mass-Spring (LMS), approximates the main subassemblies of the vehicle using a simplified mass-spring system. The paper shows a analytical model for study of the FI behavior of the vehicle with a fixed non-deformable barrier. The principal subassemblies of the FC are approximate with concentrated mass points. These concentrated masses are connected by elastic elements. The generalized coordinates of the displacements of the centers of gravity of the bodies in the longitudinal direction are set. The equations of motion will be obtained based on Lagrange’s generalized equations. Initial conditions are required for the model. Solving the system of differential equations is done using the modeling and simulation environment provided by the Matlab Simulink program. Finally, the evolution of the system’s deformation, speed and deceleration over time is graphically represented.
The LPG-diesel fuel dual fuelling effect on diesel engine performance
Authors: Nemoianu L
Published: October 2022

The use of alternative fuels can improve the performance of diesel engine in terms of pollution, [1], [2], [3].Low-carbon fuels [2] can successfully replace conventional fuels in modern engines or in future engines [1]. This may be an efficient method to ameliorate the exhaust emissions for engines of 2050, especially in terms of CO2reduction, an important issue at the internal combustion engines of automotive fleets. The liquid petroleum gas, [1-5] which has a low carbon content comparative to diesel fuel can be a good solution in terms of fuelling. The paper presents an analysis of the experimental results obtained at the speed of 3900 rev/min for three loads: 40%, 55% and 70% for dual fueling with diesel fuel and LPG. At 40% load, at dual fueling, the brake specific fuel consumption (BSFC) is reduced by a maximum of 3.5% for xc = 8.14 comparative to classic fueling and at higher LPG doses the reduction is 1.88%. At 55% load, the dual fueled engine efficiency is similar to that of the classic engine, but for xc=0.37…0.43 the BSFC is reduced by 0.6%…1.2% compared to xc=0.18…0.32. At 70% load there is a continuous improvement in engine efficiency, the BSFC decreasing at dual fueling, especially at all degrees of substitution greater than xc = 0.2, compared to conventional engine. Generally, at dual fueling, the maximum pressure does not exceed the values recorded for classic fueling. At partial load 40% the NOxdecrease with 29% for xc=21,57, by up to 17.7% at a maximum xc at a 55% load and by up to at 22.3% at 70% load. Reduction of HC emission level by up to 52.5% at 40% load, by up to 85.7% at 55% load and by 98.3% at 70% load, respectively. For smoke emission, the opacity level is reduced by up to 67.5%, at 40% load, by 50% at 55% load and by 39.13% at 70% load; the smoke number is reduced by up to 66.6% at 40% load, by 55.5% at 55% load and by up to 45.4% at 70% load. The CO2emission level is reduced by 9.4% at 40% load, 3.1% at 55% load and 6.58% at 70% load, respectively, for the maximum substitution rate used at each operating regime.
Zonal cooling principle model engine. Experimental results
Authors: Ulian T M , Rakosi E , Manolache G , Ciobotar C
Published: October 2022

This paper provides a detailed analysis of the tests performed with a spark ignition engine with zonal cooling. Zonal cooling principle assumes two cooling circuits, one for the cylinder head and one for the cylinder block and a continuous adjustment of cooling temperature in accordance with the working principle. In order to test the proposed solution, it was necessary to create a functional model of the engine with zonal thermal regime, an aspect that led to the redesign of some subassemblies and parts in order to reach the desired requirements. In this sense, the criteria related to the adaptability of these solutions on the structure of current engines were considered, first, but also those related to technological facilities, reliability, simplicity, and low cost. The above considerations led to use for experiments, a car engine with a current architecture and construction. Thus, the functional model is based on a spark ignition engine, powered by a single point injection system. An engine with the cylinder capacity of 1600 [cm3] is relatively common in car equipment variants, which was a reason for choosing this type of engine.
Heat transfer analysis of roll-bond evaporator in a small-scale household refrigerator operating with R600a
Authors: Hmood K S , Al Qaisy S J , Pop H , Apostol V , Al Douri J , Badescu V
Published: October 2022

This paper presents the experimental and theoretical assessment of the thermal behaviour of a roll-bond evaporator in a small-scale household refrigerator using the refrigerant R600a as a working fluid. The experimental data were compared with a general correlation employed to evaluate the heat transfer convection (HTC) and radiation of vertical and horizontal plates of the roll-bond evaporator. The evaporator is placed at the top side of the refrigerator. To provide the right boundary state of the evaporator, the refrigerated chamber was taken into consideration. The acquisition data system and experimental setup are described. The local radiation and convective heat transfer coefficient (CHTC) were determined for variation in heating power. In the case of small refrigerated spaces, the heat transfer through radiation cannot be neglected. The CHTC of internal vertical walls is lower than that of exterior walls. The refrigerator is equipped with an electric static heater to provide the corresponding cooling capacity. The steady-state cooling capacity predictions based on refrigerant enthalpy differences and heat source energy equation balancing were 9.66% and 0.88 % higher than manufacturing data. The results achieved a good agreement when the theoretical and experimental data are compared.
Constant pressure combustion of gaseous mixture of natural gas and hydrogen and evaluation of harmful emissions
Authors: Lucăcel M F , Darie S , Bălănescu D T , Dumitraşcu G
Published: October 2022

The paper makes a comparison of noxious resulting from constant pressure combustion of natural gas and of gaseous mixture natural gas and hydrogen. They were considered different combustion pressures and different adiabatic temperature of combustion. They were evaluated the excess air, the flue gases composition function of the pre-heating air temperature.
Neutral red dye adsorption on carbon nano-onions: viability assay interference and adduct characterisation
Authors: López Y C , Chao-Mujica F J , García-Rodríguez L M , Perez-Guevara O L , Antuch M , Reguera E , Desdin-García L F , Garcia-Hernández L
Published: October 2022

Carbon nano-onions (CNO) are versatile carbon nanomaterials with many potential biomedical applications. In this work, the interaction of submerged arc discharge in water (SADW) produced CNOs with the neutral red (NR) dye was studied. This dye is used in the in vitro toxicity NR assay, one of the most commonly used dye-based procedures to determine cell viability. Firstly the NR assay was carried out in murine fibroblast cell cultures exposed to CNOs. It was demonstrated that this assay produced invalid results due to the strong adsorption of NR on the CNOs. Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS) studies confirmed the effective adsorption of the NR on CNOs and π-π stacking as the main interaction between them. The adsorption of NR on the CNOs was evaluated by studying the decrease of the dye solution absorbance. The influence of different experimental conditions such as pH and CNOs dosage was evaluated: absorbance was found to diminish with the CNO dosage. For the maximum dosage used of 240 μg ml−1, the highest absorbance drops of −85% at pH 7 and −78% at pH 4 were registered. The adsorption process was found to be described best by a pseudo-first order (PFO) kinetics model (R
2 = 0.99), with a kinetic adsorption constant of k
1 = 0.02 min−1 and achieving an estimated sorption capacity of 3866 mg of dye per gram of CNOs. This is one of the highest values ever reported for dyes’ adsorption on carbon materials. Lastly, density functional theory (DFT) calculations were carried out to gain further insights into the interaction. These studies suggest a CNO highest occupied molecular orbital (HOMO)/NR lowest unoccupied molecular orbital (LUMO) electron density transfer as the main orbital interaction.
Mass ratio-dependently tunable enhancement of the optical nonlinearities of SnO2/RGO composites
Authors: Chen Shihao , Zhu Baohua , Xing Tinglun , Yang Jiejuan , Gu Yuzong
Published: October 2022

The composite of graphene and semiconductor nanoparticles has attracted increasing interest in the search for novel nonlinear optical materials. Herein, composites of reduced graphene oxide (RGO) and SnO2 nanoparticles with different mass ratios were synthesized via a facile hydrothermal method. The structural morphology and basic physical properties of the SnO2/RGO composites were characterized using TEM, SEM, XRD, Raman, XPS and UV–Vis spectra, indicating that SnO2 nanoparticles were uniformly anchored on the surface of graphene nanosheets through covalent and partial-ionic bonds. The third-order optical nonlinearities of the composites were studied for the first time by the Z-scan technique using a picosecond laser at 532 nm. It was found that the composites demonstrated saturable absorption and positive nonlinear refraction properties, and both were significantly enhanced compared with pure SnO2 nanoparticles and RGO nanosheets, and the enhancement was tunable with the variation of SnO2:GO mass ratio. The maximum saturable absorption coefficient and the third-order susceptibility of the as-prepared SnO2/RGO composites were obtained to be −2.93×10–11 m W−1 and 2.25 × 10–11 esu, respectively. The maximum saturable absorption modulation depth obtained was 10% with the corresponding saturation light intensity of 0.3 GW cm−2. Moreover, the optimised third-order susceptibility of SnO2/RGO was found much greater than many other materials ever studied. Several involved factors contributing to the nonlinearities were discussed. The results propose that the third-order optical nonlinearities of SnO2/RGO and other similarly structured composites can be potentially tuned to meet certain application requirements of nonlinear optical devices by controlling the mass ratio of semiconductor to graphene.
On an extended Filon method for highly oscillatory integrals over a simplex
Authors: Gao Jing , Iserles Arieh
Published: October 2022

We study a Filon-type method for the computation of multivariate highly oscillatory integrals over a general simplex. A new kind of multivariate Hermite interpolation is proposed. The existence of the multivariate Hermite interpolation leads towards the construction of an extended Filon-type methods. Such methods attain good accuracy for all values of the oscillatory parameter when increasing, as required, the interpolation order. Numerical experiments are provided to illustrate the effectiveness of our approach.
Super-localization of elliptic multiscale problems
Authors: Hauck Moritz , Peterseim Daniel
Published: October 2022

Numerical homogenization aims to efficiently and accurately approximate the solution space of an elliptic partial differential operator with arbitrarily rough coefficients in a

d
d

-dimensional domain. The application of the inverse operator to some standard finite element space defines an approximation space with uniform algebraic approximation rates with respect to the mesh size parameter

H
H

. This holds even for under-resolved rough coefficients. However, the true challenge of numerical homogenization is the localized computation of a localized basis for such an operator-dependent approximation space. This paper presents a novel localization technique that leads to a super-exponential decay of its basis relative to

H
H

. This suggests that basis functions with supports of width

O

(
H

|

log
⁡
H

|

(
d
−
1
)

/

d

)

\mathcal O(H|\log H|^{(d-1)/d})

are sufficient to preserve the optimal algebraic rates of convergence in

H
H

without pre-asymptotic effects. A sequence of numerical experiments illustrates the significance of the new localization technique when compared to the so far best localization to supports of width

O

(
H

|

log
⁡
H

|

)

\mathcal O(H|\log H|)

.
A novel augmented Lagrangian method of multipliers for optimization with general inequality constraints
Authors: Liu Xin-Wei , Dai Yu-Hong , Huang Ya-Kui , Sun Jie
Published: October 2022

We introduce a twice differentiable augmented Lagrangian for nonlinear optimization with general inequality constraints and show that a strict local minimizer of the original problem is an approximate strict local solution of the augmented Lagrangian. A novel augmented Lagrangian method of multipliers (ALM) is then presented. Our method is originated from a generalization of the Hestenes-Powell augmented Lagrangian, and is a combination of the augmented Lagrangian and the interior-point technique. It shares a similar algorithmic framework with existing ALMs for optimization with inequality constraints, but it can use the second derivatives and does not depend on projections on the set of inequality constraints. In each iteration, our method solves a twice continuously differentiable unconstrained optimization subproblem on primal variables. The dual iterates, penalty and smoothing parameters are updated adaptively. The global and local convergence are analyzed. Without assuming any constraint qualification, it is proved that the proposed method has strong global convergence. The method may converge to either a Karush-Kuhn-Tucker (KKT) point or a singular stationary point when the converging point is a minimizer. It may also converge to an infeasible stationary point of nonlinear program when the problem is infeasible. Furthermore, our method is capable of rapidly detecting the possible infeasibility of the solved problem. Under suitable conditions, it is locally linearly convergent to the KKT point, which is consistent with ALMs for optimization with equality constraints. The preliminary numerical experiments on some small benchmark test problems demonstrate our theoretical results.
N-of-1 Trials vs. Usual Care in Children With Hypertension: A Pilot Randomized Clinical Trial
Authors: Samuel Joyce P , Bell Cynthia S , Samuels Joshua A , Rajan Celin , Walton Adrienne K , Green Charles , Tyson Jon E
Published: October 2022

Background

Blood pressure (BP) is often inadequately controlled in children treated for hypertension, and personalized (n-of-1) trials show promise for tailoring treatment choices. We assessed whether patients whose treatment choices are informed by an n-of-1 trial have improved BP control compared to usual care.

Methods

A randomized clinical trial was conducted in a pediatric hypertension clinic in Houston from April 2018 to September 2020. Hypertensive adolescents and young adults 10–22 years old were randomized 1:1 to a strategy of n-of-1 trial using ambulatory BP monitoring to inform treatment choice or usual care, with treatment selected by physician preference. The primary outcome was the proportion of patients with ambulatory BP control at 6 months in a Bayesian analysis.

Results

Among 49 participants (23 randomized to n-of-1 trials and 26 to usual care), mean age was 15.6 years. Using skeptical priors, we found a 69% probability that n-of-1 trials increased BP control at 6 months (Bayesian odds ratio (OR) 1.24 (95% credible interval (CrI) 0.51, 2.97), and 74% probability using neutral informed priors (OR 1.45 (95% CrI 0.48, 4.53)). Systolic BP was reduced in both groups, with a 93% probability of greater reduction in the n-of-1 trial group (mean difference between groups = −3.6 mm Hg (95% CrI −8.3, 1.28). There was no significant difference in side effect experience or caregiver satisfaction.

Conclusions

Among hypertensive adolescents and young adults, n-of-1 trials with ambulatory BP monitoring likely increased the probability of BP control. A large trial is needed to assess their use in clinical practice.

ClinicalTrials.gov

NCT03461003

Clinical trial registry

ClinicalTrials.gov; NCT 03461003
Normative Reference Values for Crystallized–Fluid Discrepancy Scores for the NIH Toolbox Cognition Battery
Authors: Iverson Grant L , Gaudet Charles E , Kissinger-Knox Alicia , Karr Justin E
Published: October 2022

Introduction

The purpose of this study was to translate NIH Toolbox Cognition Battery (NIHTB-CB) Crystallized–Fluid discrepancy scores into research and clinical practice with adults by providing normative data for discrepancy scores for both age-adjusted standard scores (SSs) and demographically adjusted T-scores.

Method

We included adult participants from the NIHTB-CB standardization sample who denied having neurodevelopmental, medical, psychiatric, or neurological conditions (n = 730; M = 47.4 years old, SD = 17.6, range: 18–85; 64.4% women; 63.1% White). Descriptive statistics were calculated for the Fluid and Crystallized composite scores and Crystallized–Fluid discrepancy score, along with correlations between the composite scores and reliability estimates of the discrepancy score. Percentiles were calculated for the discrepancy score, with stratifications by the gender, education, and Crystallized composite for the age-adjusted SSs and demographically adjusted T-scores (T).

Results

Crystallized–Fluid discrepancy scores ranged from −40 to 44 (M = −0.63, SD = 14.89, Mdn = −1, interquartile range [IQR]: −11 to 10) for age-adjusted SSs and from −29 to 27 (M = −0.39, SD = 10.49, Mdn = −1, IQR = −8 to 7) for demographically adjusted T-scores. Crystallized–Fluid discrepancy scores of SS = 15 and T = 11 were at the 16th percentile (1 SD below the mean) and discrepancy scores of SS = 21 and T = 15 were at the 7th percentile (1.5 SD below the mean).

Conclusions

Crystallized–Fluid discrepancy scores may be, with future research, a useful within-person interpretive approach for detecting a decline from pre-injury or pre-disease levels of cognitive functioning. These normative reference values assist clinicians and researchers in determining the frequency at which given Crystallized–Fluid discrepancy scores occurred among healthy adults in the normative sample.
Changes in Glucose Control and Lipid Levels Following Trunk-Based Body Contouring Surgery in Postbariatric and Nonbariatric Patients
Authors: Henderson Joshua T , Koenig Zachary A , Woodberry Kerri M
Published: October 2022

Background

Despite consistent interest over the past 2 decades regarding the metabolic effects of body contouring (BC), previous studies are limited by short follow-up periods, small sample sizes, gender-specific cohorts, and assessment of all anatomic regions together.

Objectives

This study evaluates the changes in glucose and lipid levels over long-term follow up after trunk-based BC and compares postbariatric with nonbariatric patients.

Methods

The retrospective cohort study included patients who underwent trunk-based BC from January 1, 2009 through July 31, 2020 at West Virginia University. A minimum 12-month follow up was required for inclusion. With BC surgery as the reference point, patients' glucose, hemoglobin A1c, and lipid levels were assessed prior to surgery and at long-term follow up. Change over time was compared between postbariatric and nonbariatric cohorts. Multivariable linear regression models were performed to assess the effect of potential confounding variables on the difference between cohorts.

Results

Seventy-seven BC patients had glucose levels evaluated during the study period, and 36 had lipid profiles obtained. Average follow up from date of BC was 41.2 months for the patients with glucose follow up and 40.9 months for those with lipid levels. From pre-BC to endpoint follow up, glucose levels mildly increased in all patients. Multivariable linear regression models accounting for age showed nonbariatric patients experience significantly improved total cholesterol levels compared to postbariatric patients (P = 0.0320). Weight loss maintained following BC was not associated with significant differences between cohorts.

Conclusions

Fasting glucose levels marginally increase in most BC patients through follow up. Nonbariatric patients generally experience more favorable changes in lipid profile following trunk-based BC than do postbariatric patients.

Level of Evidence: 3
BJS-01 SARCOPENIA AND VISCERAL FAT IN PATIENTS WITH INCISIONAL HERNIA AFTER URGENT LAPAROTOMY
Authors: Romano L , Fiasca F , Mattei A , Tersigni L , Gianneramo C , Schietroma M , Carlei F , Giuliani A
Published: October 2022

Aim

Various risk factors have been associated with the development of incisional hernia (IH). Some recent papers underlined that visceral fat could be a reliable indicator. Another risk factor which is of increasing clinical interest is sarcopenia. Recent studies have identified it as an independent predictor of poor postoperative outcomes following abdominal surgery. We aimed to investigate the role of visceral fat and skeletal muscle as emerging risk factors for IH after urgent laparotomy.

Material & methods

Patients aged 18 years or older who underwent urgent median laparotomy and with continuous direct suturing of the laparotomy were included. They were categorized into two groups: those with a median IH and those without IH at 12-months follow-up. Demographic data were prospectively collected while CT scans were retrospectively reviewed. The data were compared among two groups.

Results

From January 2018 to May 2021, 364 patients underwent urgent surgery in our Department, of whom 222 were aged >18 years-old and underwent median laparotomy. Forty-four patients had diagnosis of median IH, while 41 patients without IH were identified as the control group. Statistically significant differences emerged for BMI and for the area of visceral fat. The association with the presence/absence of sarcopenia was not significant.

Conclusions

When surgery is performed in urgent settings it could be important to identify patients at risk, especially as CT scans are generally available for all patients with urgent abdominal disease. In these patients a prophylactic mesh placement could be evaluated.
OC-009 SYNGENEIC VERSUS ALLOGENEIC NON-VASCULARIZED RECTUS FASCIA TRANSPLANTATION IN A RABBIT MODEL WITHOUT IMMUNOSUPPRESSION: SHORT TERM OUTCOME
Authors: Van De Winkel N , Mori Da Cunha M , Pirenne J , De Hertogh G , Fehervary H , Miserez M , Terrie L , Muylle E , D'hoore A , Ceulemans L
Published: October 2022

Background and aim

Transplantation (Tx) of non-vascularized rectus fascia (NVRF) is a valid option in solid organ transplant recipients to avoid open abdomen after Tx. To extrapolate this technique for non-Tx patients, we investigated in a preclinical rabbit model the feasibility of transplanting NVRF in a syngeneic (Syn) versus allogeneic (Allo) strain without using immunosuppression (IS). Short-term outcome was evaluated after 4 weeks.

Material and methods

A validated rabbit model of NVRF Tx was used comparing 6 Syn New Zealand White (NZW) rabbits versus 6 Allo Mixed breed to NZW Tx without IS. Animals were macroscopically analyzed at harvesting after 4 weeks for graft integration, herniation, adhesions, seroma, hematoma, and surgical site infections. Histological and immunohistochemical analysis was performed to assess inflammatory cell reaction and neovascularization. Mechanical testing was performed to assess the thickness, stiffness and strength.

Results

Results showed similar sufficient macroscopic ingrowth of the NVRF in both groups. At the histological level, cell infiltration suggested a clearing reaction more than a rejection-based inflammation, which was more pronounced in the Allo group. No significant differences were seen concerning mechanical properties.

Conclusions

In a validated rabbit model of NVRF Tx, we showed that Tx was possible in an Allo strain without the need for IS, resulting in satisfying short term inflammatory and mechanical outcomes. Longer-term experiments are needed to evaluate the effect of graft integration and possible hernia development.
OC-014 FAVOURABLE OUTCOMES AFTER RETRO-RECTUS (RIVES-STOPPA) MESH REPAIR AS TREATMENT FOR NON-COMPLEX VENTRAL ABDOMINAL WALL HERNIA, A SYSTEMATIC REVIEW AND META-ANALYSIS
Authors: Den Hartog F , Sneiders D , Darwish E , Yurtkap Y , Menon A , Muysoms F , Kleinrensink G J , Bouvy N , Jeekel J , Lange J
Published: October 2022

Aim

Ventral abdominal wall hernia is a common problem, tied to increasing frailty and obesity of patients undergoing surgery. For noncomplex ventral hernia, retro-rectus (Rives-Stoppa) repair is considered the gold standard. Level-1 evidence confirming this presumed superiority is lacking. The aim of this study was to assess prevalence of hernia recurrence, surgical site infection (SSI), seroma, serious complications, and mortality.

Material & Methods

Five databases were searched for studies reporting retro-rectus repair. Randomized and non-randomized studies were included. Outcomes were pooled with random-effects models.

Results

Ninety-three studies representing 12,440 patients undergoing retro-rectus repair were included. Pooled hernia recurrence was estimated at 3.2% [95% confidence interval (CI): 2.2%–4.2%, n = 11,049] after minimally 12 months and 4.1%, (95%CI: 2.9%–5.5%, n = 3830) after minimally 24 months. Incidences of SSI and seroma were estimated at respectively 5.2% (95%CI: 4.2%–6.4%, n = 4891) and 5.5% (95%CI: 4.4%–6.8%, n = 3650). Retro-rectus repair was associated with lower recurrence rates compared to onlay repair (odds ratios (OR): 0.27, 95%CI: 0.15–0.51, P < 0.001) and equal recurrence rates compared to intraperitoneal onlay mesh (IPOM) repair (OR: 0.92, 95%CI: 0.75–1.12, p = 0.400). Retro-rectus repair was associated with more SSI than IPOM repair (OR: 1.8, 95%CI: 1.03–3.14, p = 0.038). Minimally invasive retro-rectus repair displayed low rates of recurrence (1.3%) and SSI (1.5%), albeit based on non-randomized studies.

Conclusions

Retro-rectus repair results in excellent outcomes, superior or similar to other techniques for all outcomes except SSI. The latter occurred less after IPOM repair, which is usually laparoscopic.