Introduction

Anterior distal femoral hemiepiphysiodesis using intra-articular plates for correction of pediatric fixed knee flexion deformities (FKFD) has two documented complications: postoperative knee pain and implant loosening. The aim of this study is to investigate the mechanical properties of a novel extra-articular technique for anterior distal femoral hemiepiphysiodesis in patients with FKFD and to compare them to the conventional technique.

Materials and methods

Sixteen femoral sawbones were osteotomized at the level of the distal femoral physis and fixed by rail frames to allow linear distraction simulating longitudinal growth. Each sawbone was tested twice: first using the conventional technique with eight plates placed anteriorly just medial and lateral to the femoral sulcus (group A) and then with plates inserted in the proposed novel location at the most anterior part of the medial and lateral surfaces of the femoral condyles with screws in the coronal plane (group B). Gradual linear distraction was performed, and the resulting angular correction was measured. Strain gauges were attached to the plates, and the amount of strain (and equivalent stress) over the plates in response to linear distraction was recorded. The two groups were compared using the Wilcoxon signed-rank test.

Results

The amount of angular correction was statistically higher in group B (extra-articular plates) at 5, 10-, and 15-mm of distraction (p < 0.001). As regards stress over the plates, the maximum stress and the area under the curve (sum of all stresses measured throughout the distraction process) were significantly higher when the plates were inserted at the conventional position (group A) (p < 0.001).

Conclusions

During anterior distal femoral hemiepiphysiodesis, the fixation of the eight plates in the coronal plane at the anterior part of the femoral condyles may produce a greater amount of correction and a lower degree of stress over the implants as compared to the conventional technique.

The overall compressive behaviour of grouted concrete hollow block prisms is dependent on the mechanical properties of both the masonry block and its grout. Grout is typically characterized by exhibiting greater longitudinal and lateral strains when compared to concrete blocks. Hence, a direct consequence is a composite-action incompatibility due to grout-to-block differential strain response under compressive loading. In order to enhance the overall composite behaviour, adding glass fibres to the grout mixture is considered in this study. The fibre-reinforced grout is expected to reduce grout longitudinal and lateral strains to be more consistent with the concrete block, which will result in better control of the cracking propagation and thus enhancing the overall ductility. This study investigates the effect of adding glass fibres to grout mix on the compressive strength and strain of the concrete masonry prisms. The presented experimental program involves testing of 36 fully grouted half-scale masonry prisms, with different glass fibre ratios (0%, 0.03%, 0.06%, and 0.10%). Twenty-four prisms were of one block thickness and two blocks in height, divided into two groups of normal and high strength blocks. The remaining twelve prisms were two blocks in thickness and five blocks in height with normal strength blocks. The prisms were tested concentrically up to failure. Results demonstrated that the addition of glass fibres to the grout enhanced the crack control as well as the post-cracking performance. The influence of adding glass fibres to the grout on increasing the masonry prisms' compressive strength was evident at high fibre percentage (i.e., 0.10%) by approximately 9.8%, 10.1 %, and 39% for the high strength two-block high specimens, normal strength two-block high specimens, and normal strength five-block high specimens, respectively.

Reinforced masonry (RM) shear walls with boundary elements (BE) have been recently presented as a ductile alternative to RM rectangular shear walls. The present study addresses the applicability of reinforcing masonry shear walls with glass fibre-reinforced polymer (GFRP) bars to attain reasonable strength and drift. GFRP-RM shear walls are a corrosion-free lateral resisting system that is transparent to magnetic fields and radio frequencies and nonconductive thermally and electrically. A numerical macro-model is developed using OpenSees to simulate the in-plane response of flexure-dominated reinforced masonry shear walls with boundary elements (RMSW-BE). The model was validated against experimentally tested walls from the literature. The boundary elements were designed with C-shaped masonry blocks. A numerical study is performed on thirty-four flexure-dominated shear walls to evaluate the influence of different design parameters on the inelastic behaviour of RMSW-BEs under quasi-static fully reversed cyclic loading. The investigated parameters are transverse hoop spacing, amount of vertical reinforcement in the boundary element, GFRP or steel reinforcement, and aspect ratio of the wall. In addition, walls with rectangular boundary elements were investigated to study the effect of increasing their size on the overall wall response. The influence of the design parameters on the hysteretic response, stiffness degradation, effective stiffness, and ductility related response modification factor was investigated to evaluate the enhancement in the seismic performance of RM buildings with RMSW-BE.

Recent advances in reinforcing lateral-load resisting systems with glass-fiber-reinforced-polymer (GFRP) bars have highlighted the need for farther experimental investigations. With the elastic behavior of GFRP-bars, ensuring sufficient plastic deformations become challenging. The current study presents the experimental work performed on six full-scale GFRP-reinforced concrete shear walls with boundary elements. The mid-rise building shear walls were tested under reversed quasi-static cyclic loading, with an emphasis on how varying the configuration of the boundary-element confinement would influence their strength and deformation performance. Two shear walls had boundaries reinforced with square GFRP spiral stirrups, while a third had boundaries reinforced with circular GFRP spiral stirrups. The remaining three shear walls had higher confinement in the boundary elements; one had a square GFRP spiral stirrups embedded inside rectangular GFRP spiral stirrups. The second had a rectangular GFRP spiral stirrups with two GFRP ties in the middle, and the third had two square spiral stirrups overlapped side-by-side. The overall performance of each specimen was characterized by investigating the hysteretic response, the cracking patterns, the drift ratio, the strength capacity, and the behavior of energy dissipation. Also, the strain progressing in the longitudinal, horizontal, stirrups, and concrete was investigated. The obtained results demonstrate that increasing the confinement level in the boundary elements enhanced deformation capacity and increased the overall strength of the GFRP-reinforced shear walls by developing a higher level of concrete compressive strains and a better distribution of shear deformations over the height.

The design of lateral-resisting reinforced-concrete elements requires prediction of the fundamental period and drift, which are determined using linear elastic dynamic analysis. To estimate the linear elastic response, the cross section of the structural element is assumed to have a linear flexural stiffness that accounts for cracking. This emphasizes the need for a reliable model for the effective stiffness in both flexure and shear response. In this study, six reinforced concrete (RC) shear walls reinforced entirely with glass fiber-reinforced polymers (GFRPs) reinforced bars were tested under reversed cyclic loading. The wall portion of all the specimens had the same dimensions: 3500 mm (137.8 in.) in height, 1500 mm (59.1 in.) in length, and 200 mm (7.87 in.) in width. The test specimens were subjected to a constant axial load of 0.15fc′Ag and a displacement-controlled lateral-loading history. The experimental results were presented and discussed to introduce the effective stiffness relationship based on cracking, failure progression, deformation, and strength degradation. The deformability factor was estimated using the serviceability and ultimate limit states based on the allowable deformation limits. A simple trilinear moment-curvature model was developed to predict the flexural response of the tested walls. A simple procedure is proposed and recommended to predict the lateral displacement of the GFRP-reinforced shear walls.

: In this paper, we studied the vibration performance, energy transfer and stability of the offshore wind turbine tower system under mixed excitations. The method of multiple scales is utilized to calculate the approximate solutions of wind turbine system. The proportional-derivative controller was applied for reducing the oscillations of the controlled system. Adding the controller to single degree of freedom system equation is responsible for energy transfers in offshore wind turbine tower system. The steady state solution of stability at worst resonance cases is studied and examined. The offshore wind turbine system behavior was studied numerically at its different parameters values. Furthermore, the response and numerical results were obtained and discussed. The stability is also analyzed using technique of phase plane and equations of frequency response. In addition, the numerical results and comparison between analytical and numerical solutions were obtained with MAPLE and MATLAB algorithms. Keywords: Vibration control, stability, offshore wind turbine system, energy transfer.

In this research, the effect of water-silica slurry impacts on polylactic acid (PLA) processed
by fused deposition modeling (FDM) is examined under different conditions with the assistance of
an adaptive neuro-fuzzy interference system (ANFIS). Building orientation, layer thickness, and
slurry impact angle are considered as the controllable variables. Weight gain resulting from water,
net weight gain, and total weight gain are the predicting variables. Results uncover the accomplishment
of the ANFIS model to appropriately appraise slurry erosion in correlation with comparing
real data. Both experimental and ANFIS results are almost identical with average percentage error
less than 5.45 × 10−6. We observed during the slurry impacts tests that all specimens showed an
increase in their weights. This weight gain was finally interpreted to the synergetic effect of water
absorption and the solid particles fragmentations immersed within the specimens due to the successive
slurry impacts.

The effects of applied load, sliding speed & temperature on the wear behavior of pure M50
alloy steel (M sample) and M50 reinforced with 10 wt.% Al2O3 (MA sample) & M50 hybrid
reinforced with Al2O3 and graphene (MAG sample) were studied. The powders were mechanically
mixed and sintered by spark plasma sintering (SPS) technique under Argon
atmosphere at 1000
C for 5 min under 35 MPa pressure. The sample surfaces were mechanically
prepared to study the wear & friction behaviors via applying mechanical polishing
using 0.05 mm diamond pastes and 1200 grit emery papers to enhance the surface
roughness. The phase structure and microstructure were estimated using XRD, Electron
Probe Micro-Analysis (EPMA, JAX-8230) and Energy Dispersive Spectroscopy (EDS, GENESIS
7000). The hardness and density of all samples were investigated according to HVS-1000
Vickers’ hardness test and Archimedes’ principles, respectively. Friction and wear tests
were carried on a high-temperature pin-on-disk tribometer (HT-1000). The investigated
samples were cut into disk-shaped specimens with 8 mm thickness and 25 mm diameter.
Then, the prepared specimens were sliding against silicon nitride (Si3N4) balls. The samples
were exposed to four different loads (2, 5, 8, and 11 N). Also, four different sliding speeds
(0.18, 0.36, 0.54, and 0.72 m/s) was performed at room temperature (RT). Another group of
samples were tested at constant applied load of 11 N and constant sliding speed of 0.72 m/s
for four different temperatures (RT, 150, 300, and 450
C). MAG exhibited enhanced tribological
properties compared with M and MA thanks to the synergic action between Al2O3

The main target of this paper is to allow renewable energy resources (RES) to participate effectively within hybrid micro
grids via an optimal proportional integral- derivative (PID) controller. This paper proposes two techniques of optimal PID
controllers in a hybrid renewable generation energy system. These techniques are particle swarm optimization (PSO) and
lightning attachment procedure optimization (LAPO). The hybrid renewable generation energy system in this study includes
a photovoltaic source, wind turbine, and battery storage, which are connected to a point of common coupling via DC/DC
boost converters. The controller at the inverter consists of a current controller and voltage source controller, which results in
three PID gains at each controller. In order to obtain the PID gains, a time domain objective function is formulated in terms
of the voltage, and current errors. The obtained results with the individual advanced optimization LAPO and PSO algorithm
are compared. The results display that the developed LAPO algorithms give better results compared to the conventional
PSO at the input and output current, voltage, and power. All the results have been taken under several operating conditions
of wind turbine (wind speed) and solar sun (changing irradiance and temperature).