Search

Superplasticiser (SP) is widely used in foam concrete industry to improve rheological properties since compaction and vibration adversely affect the stability of foam bubbles. This study aims to investigate the effect of polycarboxylate SP contents on the properties of foam concrete. Different water-cement ratios (w/c) were used, and the SP added to the mixture to adjust the spreadability. The density of 1500 kg/m3 was chosen for the production of foam concrete for semi-structural applications. Fresh, mechanical, transport and microstructure properties were analysed in this study. The results of this study showed that the content of w/c and SP had a significant impact on the performance of the foam concrete. Increasing the SP content enhanced the foam concrete’s mechanical and transport properties, but the best behaviour was through the use of 1.35% of SP. Smaller pore diameter, better pore distribution and higher portlandite peak intensity were achieved through the use of the SP. Overall, the superior behaviour of the foam concrete was achieved by the use of 1.35% polycarboxylate SP.

This paper presents the experimental results of bond and anchorage behaviours under Steel Strap Tensioning Technique (SSTT) confined high-strength concrete (HSC). The experimental tests consisted of pull-out test with short bond length and pull-out test with long bond length were performed to determine the bonding and anchorage capacity of SSTT-confined HSC. A total 36 specimens with short bond length and 16 specimens with long bond length were tested in this study. Three batches of concrete with compressive strength of 30 MPa, 60 MPa and 90 MPa were tested. Other parameter in this study was rebar diameter of 12 mm and 16 mm and different SSTT confinement ratios ranging from 0 to 0.2. To determine the effects of confinement on development bond and anchorage, an analytical expression was developed based on the parameters tested in this study. The equation is then verified with the bond strength proposed by the existing bond equations. The results from conducted tests indicated that the application of SSTT as an external confinement can increase the bond strength of confined concrete by up to 50%.

Research focusing on the effects of pre-damaged level on the effectiveness of concrete repairing using external confinement is quite limited. In addition, the use of active confinement in concrete repair works is yet to be explored. This study extends the investigation on repairing reinforced concrete (RC) columns to the active-typed confinement. Experimental tests were conducted to investigate the applicability of active confinement in repairing RC columns with varied pre-damaged levels. The applicability of steel strapping confinement in repairing RC columns with the varied pre-damaged levels was confirmed through experimental works, which involved testing of 21 RC columns under monotonic uniaxial compression. The overall responses of the specimens were investigated in terms of crack pattern, load carrying capacity, axial displacement, stiffness and ductility of repaired columns. The test results have shown that the restorability of confinement was significantly affected by pre-damaged levels. It is also observed that the increase in confining volumetric ratio can restore both strength and ductility of repaired RC columns up to 171% and 172%, for the same pre-damaged level.

Shape memory alloys (SMAs) have been considered as actuators for micro application due to its high strength to weight ratio. Although it is mostly considered for linear or rotary actuation, in this study a technique using a temperature feedback control system has been proposed to produce oscillation at steady state suitable for flapping wing actuation in micro air vehicles (MAVs). A proportional-integral-derivative (PID) controller was used in the temperature feedback system to tune the frequency of oscillation of the shape memory alloy actuator. This system is compact as the oscillation can be produced without using components to translate from linear to rotary motion. Another challenge to be addressed is the slow cooling rate of the SMA actuator that occurs through natural convection resulting in slower flapping actuation. Thus, a viable approach to improve the actuation response is by coating the SMA to reduce hysteresis. An experimental study was conducted to evaluate the effects of heat convection on the SMA actuator's control performance by using SMA wire coated with silicone rubber. Its actuation was compared to the uncoated SMA wire to establish the effects of heat convection on SMA actuation behaviour. The response of the temperature feedback system of the SMA actuator for the flapping actuation under wind loading was evaluated using wind tunnel testing. The experimental results show that coated SMA wire resulted in increased actuation frequency. However, this effect became negligible as the airflow provided sufficient cooling and resulted in higher flapping frequency at Reynolds number greater than 7.5 × 103. Wind tunnel testing demonstrated that shape memory alloy actuators using a PID based temperature feedback control system may be used to produce flapping actuation at low Reynolds numbers. Refereed/Peer-reviewed

For a Lightweight Foamed Concrete (LFC) to efficiently function as an energy-saving building material, its self-weight (density) should be reduced. However, the problem associated with a reduced density is a decline in strength. To improve the mechanical properties of LFC, this research attempts to integrate banana fibre into LFC composite with a focus on fresh and harden state properties. An Ultra-Lightweight Foamed Concrete (ULFC) with a density of 600 kg/m3 was produced with the inclusion of treated and untreated banana fibres. The volume fractions of banana fibre added into LFC were 0.00% (control specimen), 0.25%, 0.35%, 0.45% and 0.55%. In addition, an optimised batch mix of ULFC reinforced with 0.35% untreated banana fibre was produced. The batches were tested for rheological, physical, and mechanical properties. Findings reveal that the workability of ULFC composites decrease with increase in fibre addition. The compressive, flexural, and tensile strengths of the alkali-treated composites were higher than the untreated banana fibre composite. SEM micrograph reveals that defibrillation of bundle fibrils due to cleaning the surface amorphous hemicellulose, lignin and pectin of the alkali-treated fibre, leads to rough surfaces and increase surface area resulting in better interfacial adhesion of the fibre with cement matrix.

The current paper examines the effects of zinc oxide nanostructure configurations, as photo-anode formations of organic solar cells, on the performance of power conversion. To this end, some experiments were conducted during which a near band edge emission red shift of ~ 0.11 eV from nanoparticles to vertically oriented nano-rods was observed. This bandgap narrowing promotes transferring of photo-excited electrons towards the conduction band of photo-anode. A ~ 48% decrease in the deep level emission intensity revealed a smaller non-radiative waves emission due to lower level of crystal disorder. Using vertically oriented zinc oxide nanorods as photo-anodes, the photovoltaic efficiency of the organic solar cell improved considerably. The nano-rod-structured photo-anodes showed a 0.22 V rise in the open-circuit voltage, from 0.76 to 0.98 V, and a 2.08 times increment in the overall conversion performance, compared to the zinc oxide nanoparticle-structured photo-anodes. This superior performance is attributed to a greater chance of charge recombination and light-trapping in the cells, more efficient light absorption, and high level of crystallinity that grants easier electron mobility for vertically oriented zinc oxide nanorods. Moreover, a lower charge-transfer resistance (0.85 Ω) was achieved due to better electro-catalytic action for oxygen reduction for vertical nanorods compared to the other two zinc oxide configurations (1.62 Ω and 4.06 Ω). This boosted the cell performance by increasing the short-circuit current density (JSC). The fabricated solar cell may contribute to sustainable and environmentally friendly electricity generation process through reducing the consumption of non-renewable energy sources.

Background Agar has been commonly used as one of the materials to fabricate magnetic resonance imaging phantoms in the past few decades. In this study, eleven agar gel phantoms with different iron (III) oxide (Fe2O3) masses were prepared. This study was aimed to evaluate the signal-to-noise ratio (SNR) uniformity and stability of agar gel phantoms with and without the addition of Fe2O3 at two different time points (TPs). Fe2O3 powder was used as a relaxation modifier to manipulate and produce various SNR, T1 and T2 values. These phantoms were scanned using turbo spin echo pulse sequence to produce T1- and T2-measurement images. The SNR was then computed by plotting 1, 3 and 25 regions of interest on the images using ImageJ software. The T1 and T2 relaxation equations were then fitted to the experimental results of SNR versus TR and SNR versus TE curves for the determination of saturation (SNRo), T1 and T2 values. Results The results demonstrated that the agar gel phantoms were able to maintain SNR uniformity but not SNR stability after 4 weeks of phantom preparation. The change in the water content and microstructure of the phantoms have no significant effect on T2 relaxation but on T1 relaxation. The T1 and T2 of the agar gel phantoms were minimally affected although there was a systemic increase in the content of the Fe2O3 powder. Conclusions It can be concluded that the agar gel phantoms exhibited the characteristics of SNR uniformity, but they showed instability of SNR at TP2. The Fe2O3 in powder form is not an effective relaxation modifier to reduce the T1 and T2 when it is introduced into the agar gel phantoms. Dissolved nanosized particles should be the focus of future studies.

The use of resistance spot welding (RSW) in the automotive industry is by far the most preferred and widely used joining technique for sheet metal parts and is likely to continue for the foreseeable future. Advanced high strength steels (AHSSs) are most commonly used in automotive structural components due to their attractive strength-ductility combinations. However, several challenges are faced during RSW including (1) complex phase transformations such as hardening of nugget due to brittle martensitic structure and softening in the heat affected zone due to martensite tempering present in base metal, cast like solidification structure of nugget (2) elemental segregation leading to grain boundary embrittlement, (3) solidification defects such as porosity and void formation in nugget, and (4) liquid metal embrittlement cracking. All of above factors contributes in degradation of joint mechanical properties. In recent years, interlayer assisted RSW, magnetically assisted RSW, and pulsed-RSW have emerged as potential methods to improve the joint mechanical performance. This review paper seeks to summarize the recent technological advances of three modified RSW processes. A comprehensive analysis of the effect of welding process parameters on metallurgical features of the weld joint, mechanical performance, and failure behaviour under different loading conditions, i.e. cross tension, tensile shear, and cyclic (i.e. fatigue), is presented. In addition, the process feasibility to various AHSS grades is also discussed. Finally, current challenges and new opportunities arising from three modified RSW processes are discussed to provide a basis for future research.

The addition of mesocarp fibre as a bio-composite material in foamed concrete can be well used in building components to provide energy efficiency in the buildings if the fibre could also offer excellent thermal properties to the foamed concrete. It has practical significance as making it a suitable material for building that can reduce heat gain through the envelope into the building thus improved the internal thermal comfort. Hence, the aim of the present study is to investigate the influence of different volume fractions of mesocarp fibre on thermal properties of foamed concrete. The mesocarp fibre was prepared with 10, 20, 30, 40, 50 and 60% by volume fraction and then incorporated into the 600, 1200 and 1800 kg/m3 density of foamed concrete with constant cement-sand ratio of 1:1.5 and water-cement ratio of 0.45. Hot disk thermal constant analyser was used to attain the thermal conductivity, thermal diffusivity and specific heat capacity of foamed concrete of various volume fractions and densities. From the experimental results, it had shown that addition of mesocarp fibre of 10-40% by volume fraction resulting in low thermal conductivity and specific heat capacity and high the thermal diffusivity of foamed concrete with 600 and 1800 kg/m3 density compared to the control mix while the optimum amount of mesocarp fibre only limit up to 30% by volume fraction for 1200 kg/m3 density compared to control mix. The results demonstrated a very high correlation between thermal conductivity, thermal diffusivity and specific heat capacity which R2 value more than 90%.

A series of γ-alumina with different pore sizes (5.7 nm–21.6 nm) and similar specific surface areas were synthesized via an organic-free method and their adsorption rates and capacities for Congo red (CR), direct blue 78 (DB78) and direct green 26 (DG26) were investigated. The kinetics study reveals that the dye adsorptions of all γ-alumina samples fit the pseudo-2nd-order model. For CR, its k2 and the pore size of absorbent are in a linear relationship at low dye concentrations. Both of the experimental results and Langmuir isotherm calculation results suggest that the dye adsorption capacities of the γ-alumina prepared in our lab are much higher than those of other γ-alumina reported in literatures. GA-1 with the largest specific area of surface and largest size of pores exhibits a CR adsorption capacity up to 4213.6 mg/g. In addition, initial dye adsorption rates of the γ-alumina prepared in-house are much higher than that of the γ-alumina prepared with the commercially available alumina under the same conditions.

Traditionally, Ultralightweight Foam Concrete (ULFC) is primarily used to replace filling excavations, ditch restoration and underground channels, because of their high porosity, water absorption and low strength. Yet, ULFC is characterized by excellent thermal properties and could be an alternative for sustainable energy-efficient building material. This study investigates the properties of an ULFC strengthened with alkali-treated banana fibre. The low density ULFC of 600kg/m3 was fabricated and strengthened with alkali-treated banana fibre. Fibre volume fraction of 0.25%, 0.35%, 0.45% and 0.55% were compared to the unreinforced specimens, serving as the control specimen (no fibre addition). Mix proportioning of 1:1.5:0.45 of cement, sand, and water was respectively adopted throughout the mix. The alkali treated banana fibre strengthened ULFC was tested for compressive strength, sorptivity and thermal properties. Morphology of the treated fibre and ULFC composites was studied using SEM micrograph. The result depicts that ULFC exhibited the optimum compressive strength of 1.1604N/mm2 with the fibre volume fraction of 0.35%. Sorptivity or rate of water absorption was testified to upsurge, after 24 hours duration at fibre volume fraction of 0.55%, recording a 56.12% increment compared to the control specimen. The finding displays that at the highest-fibre volume fraction of 0.55%, thermal conductivity and diffusivity decrease by 13.17% and 28.16%, correspondingly, whiles the specific heat capacity increases to 37.17% all compared with unreinforced specimens. SEM images reveal that the presence of lumen and the nature of porous and fibrous alkali-treated banana fibre. Hence, it is endorsed that ULFC produced with alkali-treated banana fibre should be utilized as an infill material for composite system.

The concern about environmental problems has inspired a of energy storage devices from natural sources. In this study, solid polymer electrolyte (SPE) films made from corn starch doped with different compositions of sodium iodate (NaIO3) were prepared via the solution casting technique. The effect of dopants on the structure, morphology and electrical properties of SPE films was analysed using X-Ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) analysis. From the XRD, it shows that the amorphous state would influence the conductivity values of SPE films. Then, the SEM observations revealed that the films seem to be rough, porous and having branch structure, which may affect the conductivity of SPE films. The maximum conductivity of SPE film is obtained from 3 wt.% of NaIO3 with a value of 1.08 × 10−4 Scm−1 at room temperature (303K). From the results, this SPE is proposed to have a great potential in future energy storage applications.

This research was aimed to examine the diesel engine’s performance and emission of secondary fuels (SFs), comprising waste plastic oil (WPO) and palm oil biodiesel (POB), and to analyze their tribological properties. Their compositions were analyzed by gas chromatography–mass spectrometry (GC–MS). Five SFs (10–50% POB in WPO) were prepared by mechanical stirring. The results were compared to blank WPO (WPO100) and Malaysian commercial diesel (B10). WPO90 showed the maximum brake power (BP) and brake torque (BT) among the SFs, and their values were 0.52 and 0.59% higher compared to B10, respectively. The increase in POB ratio (20–50%) showed a negligible difference in BP and BT. WPO70 showed the lowest brake-specific fuel consumption among the SFs. The brake thermal efficiency (BTE) increased with POB composition. The maximum reductions in emission of hydrocarbon (HC, 37.21%) and carbon monoxide (CO, 27.10%) were achieved by WPO50 among the SFs. WPO90 showed the maximum reduction in CO2 emission (6.78%). Increasing the POB composition reduced the CO emissions and increased the CO2 emissions. All SFs showed a higher coefficient of friction (COF) than WPO100. WPO50 showed the minimal increase in COF of 2.45%. WPO90 showed the maximum reduction in wear scar diameter (WSD), by 10.34%, compared to B10. Among the secondary contaminated samples, SAE40-WPO90 showed the lowest COF, with 5.98% reduction compared to SAE40-WPO100. However, with increasing POB content in the secondary contaminated samples, the COF increased. The same trend was also observed in their WSD. Overall, WPO90 is the optimal SF with excellent potential for diesel engines.

In this study, a low-cost thermoset such as unsaturated polyester resin (UPR) was used for the preparation of lightweight and thermal insulation polymer composite using rice husk-derived silica aerogel (SA) as filler. For the first time, hydrophilic and hydrophobic silica aerogel (SA) of similar physical properties were added to the UPR to study the effects of SA surface polarity on the mechanical tensile and thermal properties of the composites. The composites with 40% and 60% of SA filler by volume were prepared via direct mixing and cured at room temperature using methyl ethyl ketone peroxide. The UPR composites were characterized and compared using density measurement, hot-disc thermal conductivity analyzer, universal testing machine, Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The results of this study indicate that the filler–matrix interaction appears to be dependent on the type of SA (hydrophobic or hydrophilic), due to noticeable differences in the data values. UPR composites containing hydrophilic SA exhibit lower density and thermal conductivity due to a higher volume of preserved SA pores. Both hydrophobic and hydrophilic SA could increase the tensile stiffness, but composite with hydrophilic SA exhibit higher fracture strain, indicating higher toughness. On the other hand, composites with hydrophobic SA produced stronger hydrogen bonding interaction which increases resin viscosity and led to rougher surface morphology. However, the addition of SA, regardless of surface polarity and volume concentration had little or no effect on thermal stability except that the composite with hydrophobic SA gives a slightly higher char yield.

In this work, (1-x) (Nd0.67Sr0.33MnO3): x (TiO2) composites with x = 0, 0.1, 0.2, 0.3 and 0.4 have been prepared to investigate the structural and electrical properties. Nd0.67Sr0.33MnO3 (NSMO) was synthesised via the solid-state reaction method before incorporated with TiO2. The addition of TiO2 nanoparticle as the secondary phase in manganite composite would favour the spin-polarized tunnelling near to the grain boundary and thus enhance the extrinsic magnetoresistance. Nevertheless, nanoparticle addition might contribute to substitution and diffusion with manganite compound as reported in literature. The effect of the TiO2 nanoparticle addition into NSMO composites has been examined by an X-ray diffractometer (XRD) and a four-point probe (4PP) system. From the thermogravimetric analysis (TGA), NSMO phase formation occurred in between 756.45 - 977.59 °C. XRD patterns showed that there is no peak shift when the TiO2 concentration increases. It can be deduced that TiO2 was segregated at the NSMO grain boundary region and its grain surface. However, a small amount of Ti atoms are expected to replace the Mn atoms in NSMO crystal system and has caused the increase in crystallite size. The electrical study showed that the presence of TiO2 nanoparticle and substitution of Ti in Mn sites have weaken the double exchange (DE) mechanism and suppressed the metal-insulator transition temperature (TMI). In addition, the insulating behaviour of TiO2 has also caused the resistivity of composites to increase drastically.

The microwave absorption properties of La0.85Ag0.15MnO3 prepared by solid state method was investigated. Analysis of X-ray diffraction data using a refinement technique confirmed the rhombohedral structure of the samples. The microstructure of the sample characterised from field emission scanning electron microscope micrographs showed irregular grain shapes with grain sizes ranging from 800 to 1500 nm. M-H curves revealed the weak ferromagnetic properties of the sample at room temperature. The real and imaginary parts of permittivity and permeability as well as microwave reflection loss were measured by a vector network analyser in the 8–18 GHz frequency range. The La0.85Ag0.15MnO3 sample showed a minimum reflection loss of –57.2 dB at 16.41 GHz, with a –10dB bandwidth (corresponding to reflection loss below –10 dB, or 90% absorption) of 2.67 GHz. The microwave absorption of La­­­­0.85Ag0.15MnO3 mainly arises from the conduction loss and domain wall motion which contributed to dielectric loss and magnetic loss, respectively.

Colossal magnetoresistive (CMR) materials have huge potential in modern application and it has been widely used in magnetic sensing industry. From the literature, an incorporation of secondary insulating phase into mixed-valence manganites could improve its extrinsic effect especially low-field magnetoresistance (LFMR). However, nanoparticle addition could lead to substitution and diffusion with its parent compound. In this work, the structural and electrical properties of La0.7Ca0.3MnO3 (LCMO) were investigated by adding the α-Fe2O3 nanoparticle with ratio of 0.00, 0.05, 0.10, 0.15 and 0.20 as the artificial grain boundaries. The LCMO compound has been synthesised using sol-gel route. The samples were chosen to sinter at 800°C to obtain the pure LCMO phase by referring to the thermogravimetric analysis (TGA). The structural properties were investigated by an X-ray diffractometer (XRD) while electrical properties were measured by a four-point probe (4PP) system. XRD patterns showed the coexistence of two phases (LCMO & α-Fe2O3). LCMO crystallised in orthorhombic structure with space group Pnma while α-Fe2O3 exhibited in hexagonal form with space group R-3c. As the content of α-Fe2O3 increases, the resistivity of the samples increases drastically. Nevertheless, the addition of iron oxide has no significant effect on the metal-insulator transition temperature (T­MI). From the XRD and 4PP analysis, it can be deduced that the α-Fe2O3 nanoparticles do not react with LCMO compound and successfully formed the La0.7Ca0.3MnO3 /α-Fe2O3 composites. The resistivity increases when the nano-sized α-Fe2O3 is added into LCMO nanocomposites due to the insulator nature of α-Fe2O3.

The present study aims to investigate the effect of in situ postweld heat treatment (PWHT) on microstructure, tensile shear properties, failure mode, and hardness distribution of resistance spot weld of dual-phase (DP590) steel. Tensile shear properties were evaluated in terms of peak load and failure energy. Results showed that welds subjected to high heat input in situ PWHT via double-pulse RSW process exhibit higher peak load and failure energy compared with conventional single-pulse weld. The improvement in mechanical performance is attributed to increased weld nugget size and the transition of failure mode from interfacial fracture mode to pullout fracture mode. Moreover, it was also found that increasing the tensile shear test velocity from 1.6 × 10−4 ms−1 (quasi-static) to 8.3 × 10−3 ms−1 for low-dynamic increased the peak load and failure energy of the weld.

A rapid, sustainable, and ecologically sound approach is urgently needed for the production of semiconductor nanomaterials. CuSe nanoparticles (NPs) were synthesized via a microwave-assisted technique using CuCl2·2H2O and Na2SeO3 as the starting materials. The role of the irradiation time was considered as the primary concern to regulate the size and possibly the shape of the synthesized nanoparticles. A range of characterization techniques was used to elucidate the structural and optical properties of the fabricated nanoparticles, which included X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy, field emission scanning electron microscopy, Raman spectroscopy (Raman), UV–Visible diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The mean crystallite size of the CuSe hexagonal (Klockmannite) crystal structure increased from 21.35 to 99.85 nm with the increase in irradiation time. At the same time, the microstrain and dislocation density decreased from 7.90 × 10–4 to 1.560 × 10–4 and 4.68 × 10–2 to 1.00 × 10–2 nm–2, respectively. Three Raman vibrational bands attributed to CuSe NPs have been identified in the Raman spectrum. Irradiation time was also seen to play a critical role in the NP optical band gap during the synthesis. The decrease in the optical band gap from 1.85 to 1.60 eV is attributed to the increase in the crystallite size when the irradiation time was increased. At 400 nm excitation wavelength, a strong orange emission centered at 610 nm was observed from the PL measurement. The PL intensity is found to increase with an increase in irradiation time, which is attributed to the improvement in crystallinity at higher irradiation time. Therefore, the results obtained in this study could be of great benefit in the field of photonics, solar cells, and optoelectronic applications.

Titanium (TiO2) has been studied and proved to be the most ideal photocatalyst due to several aspects such as high photoactivity, thermal and chemical stability, relatively inexpensive and non-toxicity. As the problem statement, the photoactivity and optical stability are the crucial aspects to synthesize an ideal photocatalyst. These aspects can be improved through the synthesize method to enhance its nanocrystal crystallinity. The purpose of this research is to synthesize the high crystalline silver-titanium (AgTiO2) nanoparticles and study its photoactivity and optical properties. The Ag-TiO2 was synthesized through the modification of caustic hydrothermal method and molten salt doping process to dope the silver nitrate (AgNO3) as a dopant agent. The photoactivity performance of high grade TiO2 and high crystallinity Ag-TiO2 were examine via a Methylene Blue Degradation (MBD) testing under both visible light and UV light. The optical properties were measured through the Surface Area BET (SBET) and UV-Vis-NIR spectrophotometer (UV-Vis). The UV-Vis results show that the 0.01%-Ag-TiO2 sample has a lowest band gap with 2.6eV compared to the commercial TiO2 (P25) and other samples. The SBET analysation shows that, the biggest surface area was formed in 0.05%-Ag-TiO2 followed by 0.01%-Ag-TiO2, un-doped TiO2 and 0.03%-Ag-TiO2. For the MBD-testing, the high crystalline Ag-TiO2 was performed a better photoactivity compared to the high grade TiO2. The 0.05%-Ag-TiO2 has the best crystallinity and morphology growth compared to 0.01%-Ag-TiO2 and 0.03%-Ag-TiO2 doping samples. The results obtained proves that, the presence of silver dopants was successfully improved the nanocrystal crystallinity of Ag-TiO2 and influenced its photoactivity performance.

Metal organic framework (MOF) is a class of porous material that has been acknowledged for its high porosity, tunable pores and distinctive chemical functionalities. This paper reviewed some of the selected MOF applied in adsorption and membrane separation for wastewater treatment. As adsorbent, certain MOF demonstrated high solute rejection and adsorption capacity, much contributed by high surface area and more active sites to bind with solutes. In another way, MOF can be incorporated as nanofiller in thin-film nanocomposite or mixed-matrix membrane. This water stable MOF inclusion has tuned the membrane chemistry and morphology to be more selective toward solute while enhancing water permeability. The stability of MOF was governed by high number of positive charge per atom, high coordination number, presence of hydrophobic functional groups and also their ability to resist coordination with water molecules. Important issues regarding with MOF in membrane had been addressed, particularly MOF agglomeration that further deteriorated membrane performance. At the end of the review, a conclusion and future perspective is suggested as remarks.

In this study, the effect of different treatments and the addition of maleic anhydride grafted polyethylene (MAPE) on the mechanical and thermal properties of Alpinia galanga (AG) fiber/high-density polyethylene (HDPE) composites were investigated. The AG fibers were pretreated with sodium hydroxide (NaOH) and then treated with 3-aminopropyltriethoxysilane (3-APE) as well as treated with p-toluenesulfonic acid (PTSA). The samples were first prepared by melt blending method before being injected to specimen dumbbell shape using an injection moulding machine. Three different fiber loadings were studied, such as 3, 6, 10 and 15 wt%. The tensile test results revealed that the NaOH and 3-APE treatments increased the tensile strength of AG/HDPE composites with the addition of MAPE at all fiber loadings, whereas tensile strength of PTSA treatment improved at 3 wt% fiber loading. The morphological studies confirmed a better adhesion between treated fiber and HDPE matrix with the inclusion of MAPE. Thermal analysis study showed that NaOH, 3-APE and PTSA treatments on AG fibers improved the thermal stability of the composites with an addition of MAPE by delaying the thermal degradation of the composites. The water absorption test proved NaOH and 3-APE treated fiber exhibited lower water absorption than other composites with the inclusion of MAPE. Overall, the results indicated that chemical treatment with NaOH and 3-APE with the presence of MAPE is a good approach towards the development of natural fiber composites.

Enormous quantities of unwanted industrial wastes are produced by various industries. As a result, the issues related to the environment and land scarcity have been raised. The utilization of indus...

BiFe1−xYxO3 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were synthesized by modified thermal treatment method. The structural, magnetic, and microwave absorption properties of the samples were studied by X-ray diffraction (XRD), field emission scanning electron microscopy, vibrating sample magnetometer (VSM), and professional network analyzer. XRD analysis indicates the phase transformation has occurred from rhombohedral R3c (x = 0.0–0.1) to orthorhombic Pnma (x = 0.2–0.4), and to cubic Fm-3 m (x = 0.5). With the increase of Y-concentrations, the average grain size was decreased from 354 to 90 nm. VSM analysis indicates the saturation magnetization, Ms and remnant magnetization, Mr at x = 0.2 was enhanced about 3.95 emu/g and 1.21 emu/g. The microwave measurements at 1 mm thickness over 8–12 GHz demonstrate that the highest absorption properties has occurred at x = 0.0 with a minimum value of reflection loss of about − 5.25 dB.

Purpose The purpose of this study to analyze the unsteady magneto hydrodynamic incompressible viscous fluid flow along the porous parallel plates in which constant periodic suction/injection takes place at lower and upper plate, respectively. By the proper choice of stream function, they obtained exact solution analytically. Velocity components are obtained from exact solution. Design/methodology/approach Emissions of the pollutants from the aviation sectors are doubled compared to 2000. There are many recent developments that are actively developed to combat the emission by increasing the performance of the Jet engines. The role of the computational fluid dynamics and the numerical approaches are crucial in terms of research and development. Findings Velocity profiles like axial and radial have been drawn for various values of M, D, α and θ. The exact solutions have been solved by differential transformation method. The closed form analytical solutions are obtained for the stream function, axial and radial velocities and flow velocity. Originality/value The effects of Darcy parameter, magnetic parameter, Suction Reynolds number and frequency parameter on lower and upper plates are discussed through graphs.

Thallium-based high temperature superconductor (HTS) with nominal starting composition (Tl0.85Cr0.15)Sr2CaCu2O7-δ (Tl-1212) was prepared using high purity oxide powders via solid state reaction method. Small amounts (0.0 – 0.15 wt. %) of cobalt ferrite nanoparticles (CoFe2O4) were added into Tl-1212 superconductors. The effect of CoFe2O4 nanoparticles addition on the critical temperature (Tc), phase formation and microstructure properties including elemental compositional analysis were studied. The samples were investigated by the characterization of electrical resistance measurement, powder X-ray diffraction method (XRD), scanning electron microscopy and energy dispersive X-ray analysis (EDX). Zero-resistance temperature (Tc-zero) was found to reduce from 97 K to 89 K with increasing of CoFe2O4 nanoparticles concentration. Most of the samples indicated a dominant Tl-1212 phase of a tetragonal structure with a minor phase of Tl-1201. SEM micrographs with EDX mapping showed that CoFe2O4 nanoparticles were well distributed in all the samples.

Recently, naturally occurring biopolymers have gained interests in its application as adsorbent for the removal of metal ions. The graft copolymerization modification of acrylonitrile monomer in the presence of ceric ammonium nitrate was successfully done on extracted recycled papers. The fabricated grafted adsorbent was analyzed by using scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) mapping, X-ray powder diffraction (XRD), as well as Fourier-transform infrared spectroscopy (FTIR). The parameters of the adsorption process were varied for the pH of the solution, concentration of Ni(II) ions, and time duration. As a result, the most optimum condition was achieved at pH 5 with 160 mg/L in a duration of 1 h, which reached 317.5 mg/g equivalent to 79.3% removal. The adsorption behavior tallied with Freundlich and Pseudo-second-order for adsorption and kinetic models, respectively. Convincingly, acrylonitrile-grafted recycled papers are able to be competitive and act as an efficient adsorbent in metal ions removal.

Adsorption technique for industrial effluent treatment as well as recovery of valuable components have been widely accepted for application. Since then, many researches on adsorption field have been established to investigate the economical yet having high separation efficiency of adsorbent for specific purpose. Biosorbent, for instance have shifted the focused of researches due to their abundant existence that can be easily converted into adsorbent, and some showed promising separation properties. However, the study on the biosorbent adsorption usually limited until the isotherm determination in batch experimental study. The dynamic behaviour of the system requires the experimental set-up in packed bed column, which is primarily controlled by the mass transfer mechanism. Mathematical expression describing the system is very useful as preliminary estimation of the system dynamic behaviour, provided by several input parameters such as isotherm parameters and mass transfer coefficients. Linear driving force (LDF) model approximation has proved its reliability to describe the dynamic behaviour of a system over a wide range of adsorption process. By taking three (3) experiments adsorption system on packed bed, the respective systems were simulated employing LDF approximation to obtain the dynamic behaviour of the system. The breakthrough curves were simulated by using the simplified mathematical model of LDF approximation. It is shown that the predicted LDF approximation give acceptable agreement to the experimental data with error of less than 15%, provided with mass transfer coefficient predicted from correlation. Overall, this work proved that it is possible to accurately determine the behaviour of the system using LDF approximation accompanied with the predicted mass transfer coefficient (MTC) from correlation and accurately determined adsorption isotherm for continuous system. Therefore, the mass transfer approximation is further used for evaluation of industrial-scaled packed bed column.

Since the foam concrete is delicate, it is important to carefully choose the additives, such as superplasticiser (SP), to be used in this type of concrete. The effect of using different types and percentages of SP on the performance of foam concrete with target density of 1500±50 kg/m3 has been investigated in this study. A sustainable material, Palm Oil fuel ash (POFA), used as a sand replacement at a level of 20% by weight. Five types of SP have been used in this study, including Sulphonated polymer-based, selected synthetic and organic polymers-based and three Polycarboxylate ether-based (PCE). Different SP contents (0.0%, 1.0% and 2.0%) have been used as a ratio of cement weight. Workability, consistency, foam stability and mechanical properties were investigated. The results showed that types and quantity of SP have a significant effect on the different properties of the foam concrete. Workability, compression strength and tension strength improved remarkably for most specimens. The use of 2% SP4, a PCE SP, showed superior workability, compression strength and tensile strength with acceptable stability.

In this work, magnesium diboride, MgB2 samples were prepared by using magnesium, Mg powder and carbon-encapsulated boron, B powder (1.35 wt% carbon) with addition of dysprosium oxide, Dy2O3 and lanthanum oxide, La2O3 as dopants. Different weight percentages with the ratio of x wt.% Dy2O3: x wt.% La2O3 were used where x = 0.00, 0.25, 0.50, 0.75, 1.00, respectively. X-ray diffraction (XRD) results confirmed MgB2 as the major phase for all the samples. Magnetization measurement showed a slight decrease of critical temperature, Tc from 38.1 K to 37.6 K with the co-addition of Dy2O3 and La2O3. Self-field critical current density, Jc at 20 K increased with the increasing of co-addition levels probably due to improved grain coupling. The highest self-field Jc obtained is 433 kA cm−2 with 1.00 wt% co-addition level. Field dependent Jc (≤4 T) at 20 K of the co-added samples is higher compared to that of the pure one. The present results show that a small amount of Dy2O3 and La2O3 co-addition into MgB2 is effective to enhance flux pinning and Jc.

Sterilization is the most important steps in the palm oil milling process prior to oil extraction. Experiments involving dry heating sterilization (SD) couple with solvent extraction of palm fruits were done to determine the relationship of palm oil yield and deterioration of bleachability index (DOBI). As a comparison, the conventional method of wet heating was used (SW). The optimum sterilization treatment parameters were determined by using response surface methodology (RSM). Central composite rotatable design (CCRD) was used to study the effects of sterilization temperature, X1 (°C) and treatment time, X2 (min) to oil yield (%), and DOBI. The sterilization temperature and time were conducted between 70 and 90 °C and 20 to 90 min, respectively. Preliminary results proved increasing temperature and time of sterilization process increased oil yield for both SD and SW. Furthermore, the DOBI showed a similar trend as the oil yield. Optimization study using SD gave the optimal response through a combination of parameters, SD: X1 = 90 °C and X2 = 68 min, where the oil yield obtained was 43.21% and DOBI 4.05. However, sterilization treatment using SW showed insignificant results (p>0.05) between temperature and time since R2 value was 0.4368 and the low degree of agreement between adjusted R2 (0.03) and predicted R2 (-2.43). It was also found SD treatment produced high DOBI value though the oil yield was lower than SW.

Objective: This study focuses on investigating the influence of the interproximal contact area and width on periodontal parameters. Materials and Methods: A total of 30 periodontitis subjects were involved in the study, and 661 teeth were selected for analysis. Periodontal parameters such as plaque score, gingiva score, clinical probing depth and radiographic bone level were recorded for each tooth. Upper and lower impressions were taken for construction of study models which were used for the measurement of interproximal contact area and width. simple linear regression (SLR) and multiple linear regressions (MLR) analysis were used to evaluate the relationship between periodontal parameters and interproximal dimension. Results: The SLR analyses consistently showed that the interproximal contact area and width were both significantly related with plaque score, gingiva score and bone level, and MLR analyses confirmed that both the interproximal contact area and width were significant predictors for each plaque score, gingiva score and bone level model. Conclusion: Within the limitation of the study, we can conclude that the interproximal contact area and width have a significant relationship with the presence of dental biofilm, gingival bleeding and bone level in the subjects susceptible to periodontal disease.

The effects of carbon nanofibers addition on transport and superconducting properties of YBa2Cu3O7−δ (Y-123) superconductor were studied. Y-123 was prepared using co-precipitation method for good quality bulk of high temperature superconducting material. Carbon nanofibers with 0.2–0.8 wt% were added into Y-123 superconductors. The samples were characterized using electrical resistance measurement for critical temperature (Tc) and critical current density (Jc), powder X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray analysis. Most of the samples indicated a dominant Y-123 phase of an orthorhombic structure with a minor phase of BaCO3 and Y-124. Onset critical temperature was found to decrease from 90.5 to 80 K with increasing of carbon nanofibers concentration. The Jc for pure sample is 11 A/cm2 at 30 K while the Jc of sample with 0.4 wt% carbon nanofibers is 830 A/cm2 at 30 K. Introduction of carbon nanofibers enhanced Jc significantly. However, further addition of carbon nanofibers in Y-123 superconductor caused degradation in Jc.

This research attempts to propose the fabrication and characterization of highly amorphous zinc silicate glasses derived from zinc oxide (ZnO) and white rice husk ash (WRHA). Three zinc silicate glasses were produced based on empirical formula (ZnO)x(WRHA)1−x where x = 0.50, 0.55 and 0.60 wt.% by using melt-quenching methods. When ZnO increased, the transparency of the three glasses increased. Meanwhile, X-ray diffraction (XRD) analysis of the zinc silicate glasses revealed that the glassy state of the zinc silicate glasses increased along with the increment of ZnO, and at lowest ZnO (0.50 wt.%), the presence of silicon dioxide (SiO2) peak were observed showing uncomplete melted of silica. Additional vibrational band due to the presence of tridymite was found in the Fourier transform infrared spectroscopy (FTIR) at lowest ZnO content supporting the XRD result while other glasses showed the formation of zinc silicate glasses with the presence of SiO4 and ZiO4 vibrational band. The zinc silicate absorption also increased as the ZnO increased as a result from the formation of non-bridging oxygen (NBO's). Hence, optical band gap of zinc silicate glasses was decreased from 4.35 to 4.23 eV as the ZnO increased due to increment of NBO's. All zinc silicate glasses showed three different emission peaks which is at 535, 596 and 728 nm correspond to green, yellow and red emission respectively. This luminescence properties of zinc silicate were attributed to the defect inside the ZnO particle.

Very high gravity (VHG) ethanolic fermentation is a promising technology used for producing bioethanol. However, the technology is often associated with the excessive amount of glucose that is entirely supplied in the beginning of the culture causing the fermentation process to be sluggish and therefore inhibits complete utilisation of glucose. The high concentration of glucose in the fermentation medium also elevates the osmotic pressure, which has a destructive effect on yeast cells. This study aims to enhance the production of VHG bioethanol from sago hampas hydrolysate (SHH) via fed-batch fermentation. The fermentations were performed in a 2-L stirred tank bioreactor. Batch fermentation was conducted as a control. Our results showed that the maximum yeast cell concentration achieved was significantly improved by 1.5-fold when the fermentation was carried out in fed-batch mode. The ethanol yield attained in the fed-batch culture represents an enhancement of 22% over that achieved in the batch culture. Moreover, the ethanol productivity achieved in the fed-batch culture was found to be increased by 1.8 times in comparison to the productivity attained in the batch culture. In general, this work provides useful insights into promising techniques for enhancing VHG fermentations in the stirred tank bioreactor employing agricultural residues as feedstocks.

A facile microwave-assisted synthesis approach was used to synthesize a high-quality CuSe nanosheets at different concentration of ethylenediaminetetraacetic acid (EDTA). Analysis of the XRD result revealed the formation of single-phase CuSe with hexagonal (Klockmannite) crystal structure. The crystallite size was found to decrease from 73.10 to 8.40 nm with an increase in EDTA concentration. EDX analysis revealed that all the samples were of the pure phase CuSe corresponding to a 1:1 atomic ratio. Three Raman vibrational modes ascribed to the vibrational bands of CuSe were detected from the Raman spectroscopy. TEM result revealed that a well-tailored layered hexagonal structure was achieved at higher EDTA concentration. The particle size obtained from FESEM micrographs was found to decrease from 75.10 to 12.20 nm with an increase in EDTA concentration. Moreover, the optical bandgap obtained from the UV–Visible diffuse reflectance spectroscopy was found to increase alongside an increase in EDTA concentration, which is attributed to the decrease in the particle size of the as-synthesized CuSe nanosheets. The maximum PL emission of all the samples was centered at 600 nm under an excitation wavelength of 400 nm. Therefore, CuSe nanosheets obtained by the described method could be of great benefit in many applications particularly in optoelectronics and solar cell applications.

Perovskite manganites have always been the research interest attributed to its intriguing colossal magnetoresistive (CMR) properties. Incorporation of an insulating secondary phase into the manganite composites has proven as an effective measure to enhance the low field magnetoresistance (LFMR). This paper reports the structural, microstructural and magnetic properties of (1-x) Pr0.7Sr0.3MnO3 (PSMO): x Al2O3 composites synthesized by the solid-state reaction method. Different compositions of nano-sized Al2O3 (x = 0.00, 0.05, 0.10, 0.15 and 0.20) were appended into the samples to investigate its effect on the physical properties. X-ray diffraction patterns show all samples exhibit polycrystalline PSMO as the major phase and strong orientation along (121) direction throughout the series. The crystal structural parameter is presented by Rietveld refinement. Nano-sized of Al2O3 has distorted the pure PSMO as changes have been observed in bond length and bond angle observed. Surface roughness and particle size show the increment along with increasing Al2O3 composition from the atomic force microscope (AFM) analysis. All samples possess the narrow hysteresis loop with weak ferromagnetic nature. The PSMO: Al2O3 presented in this study is a promising manganite composite which can be utilized in the magnetic sensor applications.

Colossal magnetoresistive (CMR) materials have been widely studied because of their huge potential in spintronic technology. An introduction of secondary phase to the manganite matrix is able to improve the low field magnetoresistance (LFMR). This method is favoured by recent research works as it requires a lower magnetic field compared to intrinsic magnetoresistance. Structural, magnetic properties and magnetotransport properties of polycrystalline (1-x) La0.67Ca0.33MnO3 (LCMO): x TiO2 composites where x = 0.00, 0.05, 0.10, 0.15 and 0.20 were investigated in this work. Polycrystalline La0.67Ca0.33MnO3 (LCMO) was synthesized via sol-gel method and pre-sintered at 800 °C before appending with nano-sized TiO2. All samples are in LCMO phase having an orthorhombic structure with space group Pnma. The crystal structural parameter is studied by using Rietveld refinement. As TiO2 content increases, the magnetization is getting higher as observed via vibrating sample magnetometer (VSM) analysis at room temperature. Magnetotransport properties of the pure LCMO sample have been studied from 80 – 220 K. The LFMR is enhanced as the temperature drops. The results have shown LCMO: TiO2 manganite composite is an excellent candidate for future magnetic sensors and memory devices.

A tunable Q-switched pulse erbium-doped fiber (EDF) laser using indium tin oxide (ITO) thin-film-based saturable absorber (SA) is proposed and demonstrated. The SA is formed by depositing an ITO layer using DC magnetron sputtering on the fiber ferrule, which can be easily fabricated in less than 200 s with thickness of 17.80 nm. The proposed tunable Q-switched pulse EDF laser is operated from 1540.0 to 1570.0 nm, covering a total wavelength of 30.0 nm. The generated output pulses displayed a repetition rate range between 21.70 and 94.34 kHz. The shortest pulse width retrieved is 3.22 µs at the maximum pump power of 378.6 mW, while the maximum pulse energy recorded is 30.29 nJ. To the best of the authors’ knowledge, this appears to be the first proposed tunable passively Q-switched pulse EDF laser using ITO that serves as SA, which can promote ITO film in the application of ultrafast photonics.

The aim of this research was synthesize YBa2Cu3O? (YBCO) and to study the effect of Al2O3 additions at x= 0.00, 0.10, 0.20, 0.50, 1.50 and 3.50 wt.%. The samples were investigated through Thermogravimetric Analyzer (TGA) and X-Ray Diffraction (XRD). All samples prepared by solid state reaction method with calcination process at 900°C and sintering process at 950°C. The TGA analysis indicated weight loss was complete at 910°C. XRD patterns showed the orthorhombic structure with lattice parameters a=3.821 Å, b= 3.880 Å and c= 11.663 Å, respectively. The Al2O3 added samples did not show any new peak however the sharpness and broadening peaks was changed. The crystallite sizes of the samples were calculated from the width of the selected peak and half maximum. The size is slowly increased by increasing the Al2O3 addition. These result indicated that addition does not affect on the structure but the crystallite sizes increase affect the morphology images

One of the criteria used to evaluate the improvement of the polymer's insulating property when nanofillers are introduced is partial discharge (PD). Nevertheless, the agglomeration of nanofillers within the polymer matrix is the key issue that prevents the insulating characteristics from improving. In light of the aforementioned, a variety of surface modification approaches have been developed to prevent nanofiller agglomeration. Plasma treatment is another emerging approach that has the potential to improve nanofiller compatibility with polymer matrices by altering the surface of the nanofillers. It is therefore necessary to investigate the efficiency of plasma treatment in improving the partial discharge properties of Low-density Polyethylene (LDPE) nanocomposites. In this study, the PD measurement according to the IEC 60270 standard has been conducted to characterize the PD endurance of the LDPE nanocomposites filled by different loading of plasma-treated silica (SiO2) and boron nitride (BN) nanofillers. The PD was measured using a CIGRE method (II) test cell. The phase-resolved partial discharge (PRPD) pattern diagram, the maximum PD magnitude, and the total PD number were used to examine the PD characteristics. The results showed that the 30-minutes plasma-treated nanocomposites had the greatest improvement against the PD activities with the lowest PD magnitude of 513 pC. Besides, it was found that the LDPE/SiO2 nanocomposites exhibited a significant improvement of the PD resistance compared to the LDPE/BN nanocomposites.

External confinement is an attraction technique to enhance strength and deformability of high strength concrete. Previous research revealed that pre-tensioned confinement is an approach to improve existing confinement techniques. However, limited experimental data are available especially for pre-tensioned steel-confined high strength concrete in square section. On the other hand, the stress distribution in confined square section and partial confinement is not clearly understood. This paper explores the compressive behaviour of pre-tensioned steel-confined high strength concrete. A new confinement-concrete interaction based on localised force and stress distribution in circular and square partial confined concrete is presented. By incorporating the confinement-concrete interaction, failure surface of confined concrete is calibrated with an experimental database. Confinement effect is then estimated based on the calibrated failure surface. This approach is shown to be more accurate than existing confinement models.

An important characteristic of a monolith is its porous structure. However, it is difficult to obtain a homogenous porous structure in a monolith due to dead-end and uneven distributions of pores, ...

Welding matrix composites that have been formed with conventional methods produce many discontinuities which harm the quality of joints. Friction stir welding (FSW) offers an alternative method to prevent these issues. However, the existence of reinforcing particles, such as silicon carbide in metal matrix composites (MMCs), has significantly increased the wear rate of FSW tools and hence, reducing their tool life. Therefore, this research has focused on the improvement of FSW tool life in joining the aluminum matrix composites, through surface enhancement. H13 tool steel and tungsten carbide, as a base material, were used for the FSW tool, and graphene, carbon nanotubes, and diamond-like carbon were chosen for coating the FSW tool. Subsequently, the wear on the FSW tool was measured before and after welding to evaluate tool life. The result of wear measurement indicates that the wear resistance of the diamond-like carbon (DLC)–coated tungsten carbide was higher than the others. The tool life of the coated tungsten carbide (WC)-DLC was prolonged to approximately 41%. In addition, it is predicted that the FSW tool can be effective for up to 1200 mm of weld joint.

Using waste tyres as recycle material in the construction industry seems to be a good solution to the problem of waste management and landfill. The main purpose of this paper is to study the behaviour of rubberized concrete-filled steel tube (RuCFST) analytically for square and rectangular columns under lateral monotonic loading. Seventy-two prototypes modelled using ABAQUS 6.12-1 software with various variables, which are cross-section shape, rubber replacement as a percentage of natural aggregate, column length, sections slenderness ratio and the axial loading level. The results showed that the adopted model in elastic and plastic properties gives a good agreement between numerical and referenced experimental results. Moreover, increasing the rubber replacement percentage has no major effect on the columns’ capacity; meanwhile increasing the columns’ length lead to decrease the strength capacity dramatically. Furthermore, increasing the axial loading percentage leads to reduce the column lateral strength. Similarly, the columns’ capacity decreases with increasing the section slenderness ratio.

This article analyzed the roughness coefficient of polyurethane-bonded revetment (PBR) by laboratory testing. A wave basin was constructed, with a regular wave generator installed. Three types of revetment were constructed at the same time in the wave basin. Scales were painted on the revetments. Video cameras were installed to record the wave run-up. Measurments of wave height and wave period during the tests were not necessary, since a run-up estimation was entirely based on a linear relationship. The PBR’s roughness coefficient could be interpolated from those of rock and concrete revetments. Three revetment slopes were tested. The roughness coefficient of the PBR was found to be in the range of 0.632 - 0.674, with a standard deviation of 0.042 - 0.053. Following this identification of the roughness coefficient of PBR, coastal engineers can now design revetment crest elevations with confidence.