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The paper focuses on developing a new numerical program to determine the frequencies, modes, and the maximum amplitudes of vibration of traction, torsion, and bending modes of an axisymmetric supersonic nozzle by finite element method (FEM), using the inverse iteration algorithm, and the spectral shift. The goal is to eschew the resonance with the frequencies of the side loads caused in the not-adapted regime when varying the nozzle pressure ratio (NPR), and consequently avoid the rupture of the nozzle and the failure of the aerospace mission. We made the modelling of the nozzle geometry by thin walled circular and variable section of finite elements for free embedded beam, since the nozzle is considered as fixed at the throat and free at the exit section. The design is made by the method of characteristics (MOC) in the framework of high temperature (HT) model for air, to determine the contour of the nozzle, giving a uniform and parallel flow at the exit section. For the bending, the shear force and rotation effects are added in the two elementary matrices. We make the application for minimum length nozzle (MLN) given its current intensive aerospace application, and with best performances nozzle (BPN), and dual expansion nozzle (DEN), aiming to present an improvement for recently developed DEN. The results demonstrate an increase in the frequencies and decrease in the maximum amplitudes in the interest of the international aerospace community, up to 101% and 679% of DEN compared respectively to MLN and BPN when the exit Mach number ME= 3.00, the stagnation temperature T0= 2000 K and the throat radius nozzle ratio λ= 0.82. We made the validation for BPN central body, since it is of a constant cylindrical section, whose solution is in the literature for a traditional beam.

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In this work, the mechanical behaviors under flexural loading of fiber–metal laminates (FMLs) comprised of an aluminum alloy reinforced with glass fibers (GFs) and Kevlar fibers (KFs) embedded in an epoxy composite are experimentally investigated. For this purpose, non-FMLs, FMLs, and hybrid FMLs (HFMLs) are tested and their results are compared in terms of the flexural strength and modulus, strain to failure, toughness, interlaminar shear strength (ILSS), and specific properties. Results show that the incorporation of GFs on the compression side and KFs on the tensile side improves the bending properties of the HFMLs compared to the KF-based FMLs, which enhances the laminates’ resistance to bending loads. The HFMLs exhibit improvements of 24%, and 5% in flexural strength and modulus, respectively, compared to the KF-based FMLs. Moreover, hybridization significantly improves strain to failure by up to 115% compared to the GF-based FMLs. Additionally, the ILSS analysis reveals improved values in FMLs compared to non-FML samples, when GF-based FMLs demonstrate higher ILSS than KF-based ones, which can be attributed to GFs’ stiffness and high-quality bonding with the aluminum sheets. HFMLs attain a 19% improvement in ILSS compared to the KF-based FMLs. The failure mechanism depends on the intrinsic features of the studied fibers, while the studied FMLs display better damage tolerance. In this context, the HFMLs present enhanced toughness, delamination resistance, and the ability to prevent crack propagation, positioning them as promising candidates for lightweight structural applications where a balance between strength, stiffness, and toughness is required.

Introduction The bio-stimulatory effects of low-intensity ultrasound on dental tissues which were clinically introduced in 2004 demonstrated a reduction in root resorption in maxillary premolars subjected to a force level of 50 g. Similar results by applying a torque of 50 g to the maxillary premolars were obtained in 2016; however, the effects of low-intensity pulsed ultrasound (LIPUS) on the presence of high-intensity forces are not yet known.Aim The purpose of this study was to examine the effects of LIPUS on a sample of 40 patients.Methods The analysis was conducted by applying two forces to teeth no. 14 and 24, each with an intensity greater than 50 g, and applied at two different points on the coronal surface. Subsequently, LIPUS was applied daily for 20 minutes to tooth no. 14, while tooth no. 24 served as a control. The study lasted for 28 days.Results Overall, the group treated with LIPUS demonstrated an improvement in the average total volume and percentage of root resorption compared to the control group. The same results emerged for the diameter, depth, and surface of the gaps of resorption.Conclusion This study showed that it was possible to reduce root resorption in the presence of forces with intensities greater than 50 g. Nevertheless, a longer period of study will make it possible to obtain more rational results as to the effectiveness of low-intensity ultrasound on root resorption induced by orthodontic treatment.

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River-carried solids, especially during floods, lead to dam sedimentation. Dredging extends dam life, but excess unusable sediment storage threatens the environment. The aim of this work is to investigate the influence of the recovery of calcined mud from Chorfa dam on the physico-mechanical and chemical characteristics of mortars fiber bundles. The sludge is used as a partial substitute for cement by volume at rates of 10%, 15%, 20% and 25%. All test specimens had water / binder (W/B) ratio and steel fibers ratio. Testing programme included measuring the fluidity, ultrasonic pulse velocity test, dynamic modulus of elasticity, flexural and compressive strengths. Compared to the control mortar, the fluidity represented by the diameter of M0, M15 and M25 mixtures decreased by approximately 11%, 14% and 22%, respectively. The compressive strength of M15 increased by 17.4% at 28 days, compared with the control specimen. At 7 days, the ultrasonic speed of the M25 mixture decreases by 1.7% compared to that of M15. The dynamic modulus of elasticity of M20 and M25 increases by 13% and 12% as the age ranges from 2 to 28 days. At 28 days, the flexural strength of the M20 blends increased by approximately 64%.

This paper proposes an adaptive, three-dimensional (3D) path-following controller for airships in the presence of wind disturbances, which explicitly considers that wind speed is time-varying. The main idea is to formulate airship path-following as control design for systems in the presence of parametric uncertainties and external disturbances. Assuming that there is no prior information on wind, the proposed solution is based on the ℒ1adaptive controller. This approach makes clear statements for performance specifications of the controller and relaxes the common assumption that wind speed is constant. This makes the design more realistic and the analysis more rigorous, because in practice, the wind speed may be time-varying. The results of the simulation indicate that the path following system has a good performance and is robust against wind disturbances.

Expanded criteria donors help to increase graft availability, but provide organs with an increased risk of delayed graft function. We aimed to investigate whether donor hypothermia decreases the risk of delayed graft function compared with normothermia.

The integer sequence π = π1‧‧‧ πnis said to be an inversion sequence if 0 ≤ πi≤ i – 1 for all i. Let ℐndenote the set of inversion sequences of length n, represented using positive instead of non-negative integers. We consider here two new statistics defined on the bargraph representation b(π) of an inversion sequence π which record the number of unit squares touching the boundary of b(π) and that are either exterior or interior to b(π). We denote these statistics on ℐnrecording the number of outer and inner perimeter squares respectively by oper and iper. In this paper, we study the distribution of oper and iper on ℐnand also on members of ℐnthat end in a particular letter. We find explicit formulas for the maximum and minimum values of oper and iper achieved by a member of ℐnas well as for the average value of these parameters. We make use of both algebraic and combinatorial arguments in establishing our results.

This work focuses on the synthesis of Bi2Fe4O9/Ag3PO4composites with different Bi2Fe4O9contents to remove the Rhodamine B (RhB) dye pollutant. The obtained composites were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Photoluminescence and UV–Vis spectrophotometry. The 5Bi2Fe4O9/Ag3PO4catalyst with 5% Bi2Fe4O9loading exhibited the high photocatalytic performance with degradation efficiency of 97.91% after 12 min under visible light irradiation. Photoluminescence and UV–Vis analysis showed that 5Bi2Fe4O9/Ag3PO4has the best separation of photogenerated e−/h+pairs and light absorption. The catalyst exhibited a good selectivity toward tartrazine and methylene blue. The cycling experiment revealed that 5Bi2Fe4O9/Ag3PO4catalyst has a good stability after 4 runs. The results of trapping radical experiments indicated that h+charge carriers were the main species involved in the RhB photodegradation process which was supported by a Z-scheme electron transfer mechanism.

The aim of this work is to develop a new numerical calculation program making it possible to correct the thrust coefficient CFand the exit Mach number MEof an existing MLNby studying the effect of the stagnation temperature T0of the combustion chamber below the dissociation threshold of the molecules, based on the use of the HTmodel to, firstly, correct the flow in the nozzle, and then deduce the new corresponding values of (CF)Cand (ME)C. The nozzle equipped with missiles and supersonic aircraft is determined using the PGmodel. This model is developed without dependence of T0. In reality, and depending on the used propellants, the combustion chamber T0value can reach high values exceeding 500 K. Since T0can be high, the (CF)Cand (ME)Ccannot be those obtained by the PGmodel. They must respond to the behavior of T0effect, since the gas actually behaves like a gas at HT. Since the MLNhas an unchanged contour, that is to say the mass of the nozzle is unchanged, it is necessary to correct the (CF)PGas well as, (ME)PGin order to further correct the other performances of the aerospace machines using the MLN, like the range, flight time, and maximum altitude of the supersonic missiles. An introduction of two new dimensionless coefficients λand ψmaking it possible to respectively determine the correction rate of (CF)Cand (ME)PGcompared to those determined by the manufacturers during the design of the MLNby the PGmodel. The calculation of the error between the obtained correction value and that given by the manufacturer is done for all parameters. The application is made for air and for three other gases H2O (gas), CO and N2. For example when (ME)PG= 3.00, T0= 3500 K, r*= 1.00 and air, we will have a correction until 21.16% for (CF)Cand 9.50% for (ME)C.

Abstract. Structural, Morphologycal and Wettability of SiliconNanowires (SiNWs) elaborated using Ag assisted electroless chemical etching are investigated. Prior the etching, Ag nanoparticles (AgNPs) were deposited at room temperature in a HF/AgNO3 solution with different concentration of AgNO3. The XRD spectra of the Ag NPs deposit show a good crystallinity. The effects of temperature etching bath and concentrations of AgNO3 on the etching process were examined. The morphological study, performed using a Scanning Electron Microscopy (SEM), shows porous silicon layer of 2µm for the lower temperature etching. For 25°C, perpendicular silicon nanowires about 15µm were formed. For the higher etching temperature (50°C), the silicon nanowire about 50 nm in diameter and 50µm in length were formed. The impact of Ag concentration on the SiNWs formation is examined in the second part of the present work. It is shown that the etching depth decreases as the Ag concentration decreases with values of 2.8 μm and 2 μm for concentrations of 0.025M and 0.0125M, respectively. The hydrophobicity of the samples was monitored by measuring the contact angle between a drop of water and the sample surface. It was established that the morphology is strongly influenced by etching conditions and their wettability changes from superhydrophilic to hydrophobic. FTIR analysis confirms the oxide-free silicon nanowires.

This paper deals with the observability of systems governed by infinite-dimensional linear conformable differential equations. By stating the duality between controllability and observability of infinite-dimensional linear systems, we provide necessary and sufficient conditions of exact and approximate observability for the conformable fractional linear system. Finally, some examples are given to illustrate our theoretical results.

This study aims to assess the chemical composition of the aqueous extract of Cistus albidusL. leaves, as well as the potential of aqueous and hydroethanol extracts of the leaves and seeds as analgesic, anti--inflammatory, and antioxidant agents. The contents of phenolics and inorganic constituents were determined in C. albidusseeds and leaves; antioxidant capacity was assessed by 3 complementary and diverse tests. The carrageenan-induced paw edema technique was used to investigate the anti-inflammatory effect in vivo, and albumin denaturation to evaluate the anti-inflammatory effect in vitro. The acetic acid-induced contortion test, the tail-flick test, and the plantar test were used to assess the analgesic effi cacy in vivo.

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Selecting the appropriate material is crucial for the successful performance of printed elements. The present study aims to develop a strong and lightweight 3D-printed sand mortar using E-glass waste powder. It evaluated the material’s fracture energy, compressive strength, and ultrasonic pulse velocity properties through three-point bending experiments. Mixture specimens were prepared with varying E-glass volume contents of 5%, 10%, 15%, and 20%. The experiment concluded that the control mixture was brittle, while the addition of E-glass increased the fracture energy of the dune sand mortar by 21% to 143%. The compressive strengths of all specimens were higher than 25 MPa and up to 48 MPa. Ultrasonic pulse velocity confirmed the high quality of the E-glassy mortar specimens. It also performed manual flow ability tests to examine the printability and buildability of the mortar mixes. Using recycled E-glass waste in 3D printing enhances the buildability and resistance to the brittleness of lightweight mortar.

We analyse the impact of tea industry specific macroeconomic factors on tea companies' share prices listed in Bombay Stock Exchange, India using quantile regression approach. We consider monthly period from January 2003 to December 2017. We find evidence to support the relationship between tea industry and tea companies' share prices. Our results reveal that the change in area of cultivation has both negative and positive impact on the share prices of tea companies. This study indicates that production of tea has a significant and only positive influence. Further, we observe a minimal impact of tea import only on three companies' share prices. This paper also notes that tea companies' share prices react most significantly to tea export.

The construction of earth dams on active faults presents a risk of instability. The Ourkiss dam, built 14 km south of the town of Ain Fakroun, is a heterogeneous type of dam made of clay and alluvial materials, with a watertight geo-membrane lining on the upstream face of the dam and on the dam flanks. Due to its location close to active faults, the dam could be damaged by instability in the event of a very strong earthquake. For this reason, in this article a comparison between two study approaches is made: one is quasi-static based on a failure analysis due to the effect of normal and reverse fault propagation. Different angles of inclination are applied by sliding through the Ourkiss dam at the end of construction and in the filled state. The other approach is based on the dynamic effect of the 2003 Boumerdes earthquake (magnitude 6.9 on the Richter scale), modeled with a sinusoidal propagation velocity applied to the model base in the horizontal direction. The results obtained for both approaches are presented in terms of shear deformations developed at the dam foundation and dike. They show that the deformation values found by the quasi-static method are greater than those found by the dynamic method.

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Reliable personal identification is crucial. This study explores an ECG-based system using spectrograms and involutional neural networks (INNs) for accurate person identification. The system first preprocesses ECG signals with a Butterworth filter and segments them using the Pan-Tompkins++ algorithm. Each segment, representing a heartbeat, is then converted into a spectrogram using the short-time Fourier transform (STFT). Finally, an INN classifies the spectrograms for identification. Tested on the MIT-BIH Arrhythmia and Physikalisch-Technische Bundesanstalt (PTB) databases, the system achieved accuracies of 97.93% and 97.63%, respectively, surpassing conventional methods like convolutional neural networks (CNNs). This improvement is attributed to INNs' ability to better capture both local and temporal patterns in the spectrogram data.

l-asparaginase catalyzes the hydrolysis of l-asparagine to l-aspartate and ammonia. In the present study, we describe the production, purification, and preliminary characterization of Dickeya solanil-asparaginase. The purification of l-asparaginase was done using ion-exchange chromatography on HiTrap Q-Sepharose Fast Flow followed by FPLC-gel filtration chromatography on Superdex 75 pg. The presence of the enzyme was confirmed by enzymatic activity measurements along with SDS-PAGE analysis. The purified l-asparaginase was shown to exhibit specificity towards l-asparagine, while being inactive against l-glutamine. This data allows us to suggest that the l-asparaginase from Dickeya solanimight be clinically more relevant than, e.g., the l-asparaginase isolated from E. coliwhich hydrolyzed also l-glutamine and produces l-glutamate, a neurotoxic agent. We also demonstrated that the enzymatic activity was enhanced in the presence of TiO2and ZnO nanoparticles, making them good candidates to improve l-asparaginase activity. Indeed, the results obtained show that the TiO2nanoparticles increased the activity of l-asparaginase by a factor of 6.0 while the ZnO nanoparticles increased it twice.

This paper aims at studying the combustion in a homemade combustion chamber of biofuel briquettes prepared from olive mill solid wastes. Two different samples of briquettes compressed under 150 MPa and 35 °C were investigated:with binder (BOMSW) by adding corn starch and without binder (OMSW). Three combustion regimes were considered:18, 36,and 55 m3/h,respectively. Seven K-thermocouples were used for temperature measurements. Moreover, the gaseous emission analysis was undertaken. Results show that the flame front propagation velocity reaches maximum values of 11 mm s−1and 8.54 mm s−1for OMSW and BOMSW,respectively. We find that the NOxcontent was higher in the case of the OMSW. On the contrary, the percentages of methane, carbon monoxide,and sulfur dioxide were more significant with the BOMSW. The combustion efficiency was evaluated and gives a higher value with BOMSW. We concluded that the used binder affects seriously the combustion efficiency and the gaseous emissions.

The Cottony Cushion Scale Icerya purchasi(Homoptera, Monophlebidae) is a citrus pest whose importance is growing due to the prohibition of broad-spectrum chemical molecules such as Chlorpyrifos Ethyl. Monitoring of the population during the 2022 and 2023 campaigns in the Aoulouz region on Nadorcott plantations revealed that the pest carries out 4 generations per year, like what has been reported in regions with a similar climate (Arizona and Iran). The recorded natural enemies of the pest are lacewings and the ladybug Rodolia cardinalis(Coleoptera, Coccinellidae). The latter is by far the most important aid in limiting infestations. The ladybug comes into activity early in the season around Mid-March. It largely contributes to controlling the pest if the evolution of its population is not disrupted by high temperatures and chemical treatments, especially those targeting thrips, aphids, and California red scale. Incubations carried out on the cottony cushion scale females collected from the same region did not reveal the presence of the parasitoid Cryptochetum iceryae(Diptera, Cryptochetidae) which has demonstrated its effectiveness in the biological control of I. purchasiin California and Israel. Trials were conducted to evaluate the impact of pesticides commonly used on citrus fruits (Spirotetramat, Spinosad, Abamectin, Pirimicarb and Sulfoxaflor) on R. cardinalisto outline an integrated control strategy against this pest on citrus fruits. All these products showed a certain selectivity towards the beneficial, which implies a certain habituation developed by the natural occurring populations of the ladybug. The control of I. purchasineeds the establishment of a monitoring system of the population of both, the pest and R. cardinalis, combined with a continuous follow-up of the climate conditions to avoid any surprises closed to the harvest period. In term of pesticide use possibilities, the tested chemicals are sufficient to achieve the control of other pests by preserving the activity of natural enemies on the cottony cushion scale. The inoculative introduction if the parasitoid C. iceryaeinto Morocco should reinforce the biological control strategy.

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Soil reinforcement encompasses a set of techniques aimed at enhancing its mechanical or physical properties by introducing inclusions that work under tension, compression, or flexion. Some of these techniques include soil nailing, anchor tiebacks, micro-piles, bored piles, and ballasted columns. In this study, we analyze the behavior of a wall anchored by five anchor tiebacks (model of the Ain-Naadja Station 02) subjected to seismic excitations based on the Boumerdes 2003 response spectrum. The analysis is carried out using 2D and 3D finite element methods with the dynamic calculation software Plaxis version 20. The obtained results are presented in terms of horizontal stresses, shear stresses, horizontal displacements, and horizontal deformations over time along the wall (piles) at three different positions: the top, middle, and base of the wall. This is done to anticipate the effect of seismic loading on the stability of the structure.

As the utilization of stratospheric airships becomes more prevalent, ensuring their safe operation becomes crucial. This paper explores the ability of an L1adaptive controller to maintain fault tolerance in the actuators of a stratospheric airship. L1adaptive control offers fast adaptation while separating adaptation and robustness. This makes the approach a suitable candidate for fault-tolerant control. The performance of the proposed design is compared to the Linear Quadratic Integral and Adaptive Sliding Mode Backstepping controllers. Simulation results show that the robustness of the airship model against faults is improved with the use of the L1adaptive controller.

Aquaculture systems produce ammonia nitrogen as a by-product of aquatic animal protein metabolism. The dropwise method was used in this study to prepare composite beads based on the chitosan (CS) biopolymer and bentonite (Bt) clay to remove ammonia nitrogen from aquaculture wastewater. The composite beads were characterised using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller analysis and environmental scanning electron microscopy. According to the FTIR analysis, CS was successfully immobilised on the surface of Bt. Furthermore, the XPS analysis revealed that the chemical surface of the chitosan/bentonite (CSBt) composite was rich in CS elements. To remove ammonia nitrogen, three samples of aquaculture effluents were collected and characterised in terms of physico-chemical and chemical aspects. The ammonia nitrogen removal from aquaculture effluents was 100, 91.8 and 87.7% for initial concentrations of 0.56, 1.72 and 2.13 mg/l, respectively. Ammonia nitrogen sorption tends to reach equilibrium in approximately 120 min. The findings also show that the kinetic data correlated well with the pseudo-second-order equation. pH values increased slightly after adsorption, and the same trend was observed for total hardness and alkalinity. As a result, the CSBt composite is a promising adsorbent for ammonia nitrogen removal from aquaculture effluents.

Multi-agent path planning is a complex problem aiming to find the shortest trajectory. In this paper, we propose a cooperative path planning based on a hybridisation of two motion behaviours. The first behaviour concerns the strategy in which the agents are independently moving to their common objective according to the detected environment's rewards. The second behaviour is based on the leader-followers strategy through which the follower agents are moving in the direction of their leader agent to achieve their objectives. The goal of this work is to provide an equilibrium between these two approaches by allowing the follower agents to move in the direction of the objective instead of following the leader in some cases to decrease the execution time. To prove the approach's feasibility, we applied it to the multi-pursuer multi-evader game in comparison with the recent approaches. The obtained results prove the efficiency of the proposed approach.

The harmonic indexof a graph Gis denoted by H(G) and is defined as H(G)=∑uv∈E(G)2du+dv, where du, dvdenote the degrees of the vertices u, v, respectively, of Gand E(G) is the edge set of G. In this paper, the graphs having sixth to fifteenth maximum harmonic indices are characterized from the class of all n-vertex trees for sufficiently large n.

The aim of this paper is to develop a new numerical program aiming to calculate the stress effect of the successive addition of the vertical spars on the reduction of the maximum tangential and normal stress due to the various internal forces, in multi-box thin-walled airfoils sections. The comparison is made with the single box airfoil without spar. The airfoil is given by tabulated values. An interpolation by cubic spline is necessary to obtain an analytical function for the upper and the lower surfaces. The calculation is based on the computation of the geometrical characteristics of the thin-walled section with different spars number. The method consists of scanning the position of the first spar along the airfoil chord, and calculating the maximum of the tangential and the normal stress, giving at the end the optimal spar position with the smallest stress values. The calculation is be repeated for the second spar based on the first optimal spar position. The insertion of a third spar is made on the optimum position of the first two spars. The calculation will be repeated each time an additional spar is inserted. The optimum spars position is not the same for the two types of torsional and normal stress. The diagrams of the internal forces are necessary to locate the dangerous section stressed by the maximum internal forces. The application is made up to five spars as an improvement to the current applications for 1 and 2 spars. Six airfoils are used for comparison.