A Study on Parameter Optimization of the Delamination Factor (Fd) in Milling Kenaf Fiber Reinforced Plastics Composite Materials Using DOE Method / Azmi Harun...[et al.]

Kenaf is known by its scientific name, Hibiscus cannabinus, which is similar to jute and cotton, and is also a warm-season annual fibrous crop. In the past, it was used to make sackcloth, and its twine was used to manufacture rope. Kenaf is also used as a cordage crop. A machine’s surface quality normally depends for its reliability in the service application. The machining process changes the mechanical and chemical properties of individual constituents used for the composite. The objectives of this research are to study the effects of milling parameters and to determine the optimum conditions for a range of milling parameters to minimize the delamination factor (Fd) in milling kenaf fiber-reinforced plastic composite using the Taguchi Method. The Taguchi Method L8 (23) design was used to conduct a non-sequential experiment. The experimental results were analyzed using the Minitab 16 software. A study was carried out to investigate the relationship between the milling parameters, and their effects on the kenaf reinforced plastic. The composite panels were fabricated using the vacuum assisted resin transfer molding (VARTM) method. This study determined that the optimum parameters for the minimum delamination factor were a cutting speed of 16 Vm/min, a feed rate of 0.1 mm/tooth, and a depth of cut of 2.0 mm. The feed rate and cutting speed made the biggest contributions to the delamination factor (Fd). The use at high spindle speeds and low feed rates led to minimized delamination factor (Fd) during the milling of kenaf reinforced plastic composite materials

Design and simulation of cascaded H-bridge multilevel inverter with energy storage

Stand-alone power system provides a solution for the user in rural areas that are disconnected from the utility grid which requires power electronics device for the power conversion. This work proposes a design of 5-level cascaded H-bridge inverter with energy storage to realize DC-AC power conversion for such system. The DC-DC bidirectional converter is designed to control the charging and discharging of current into/from the battery during the buck and boost mode of operation. At the DC side, dual-loop control strategy using PI controllers is designed to control the current and voltage. The inner loop current controller controls the recharging/discharging of current for the battery, while the outer voltage controller controls the DC link voltage at 200 V for each of the H-bridge unit. At the AC side, multiple feedback loop control strategy regulates the inverter output voltage at 240 Vrms under various load change. The modelling and design of the system is implemented under Matlab Simulink environment. From the results, the battery storage unit works well with the DC link voltage to achieve a balance power transfer within the system between the PV source, load and battery storage under variation of PV power and loading condition

On The Use Of Nano Fibrillated Kenaf Cellulose Fiber As Reinforcement In Polylactic Acid Biocomposites

In this study, nano fibrillated kenaf cellulose (NFKC) derived from kenaf fiber after varying chemico-mechanical treatments were introduced into poly lactic acid (PLA) as reinforcements to improve the mechanical and morphological properties of the biocomposites. The new strategy was aiming to realize the synergistic effects of chemical treatment and mechanical fibrillation process parameters (blending speed and time) for yielding nanofibers and its reinforcement effects on the properties of biocomposites. The yield percentage of the NFKC was determined using centrifugal method and the NFKC fibers with PLA pellet were hot pressed to form NFKC-PLA composites. The distribution and dispersion morphologies of NFKC in NFKC-PLA composites were observed by using optical microscope (OM) and scanning electron microscope (SEM). The reinforcing effect on the mechanical properties of NFKC-PLA composite was investigated by tensile strength test. Average length and diameter of fibrillated fibers were decreased with the concurrent increase of blending speed and time. The maximum increase in tensile strength of 59.32% and elongation of 100% were observed for NFKC-PLA composite with NFKC yielded at a blending speed and time of 15000 rpm and 15 minutes as compared to pure PLA. The tensile properties indicated that the strength and modulus were improved with increased nanofiber contents

Insect diversity and abundance during the crepuscular and nocturnal temporal periods in the Kota Gelanggi limestone complex, Pahang, Malaysia

The diversity and abundance patterns of nocturnal insect orders during the crepuscular and nocturnal periods, 6pm-9pm, 10pm-1am and 4am-7am at Kota Gelanggi limestone complexes were investigated. The insects were collected by using light traps over a period of six months from May to October 2014. A total of 35 732 individuals from 19 orders were captured. Coleoptera (n=14 103, 39.5%), Hymenoptera (n=10 030, 28.1%) and Diptera (n=4 821, 13.5%) were the most abundant orders. The results showed a bimodal pattern in the abundance of insects where more were caught during dusk followed by dawn and the lowest during the nocturnal period. However there was no significant difference (F= 0.71, df= 2, P> 0.05) in insect abundance between the three sessions. Studies on nocturnal insect activity patterns give us an understanding of the behaviour of the insects especially agricultural pest insects, and this information is necessary to develop effective pest control management

Study the Effect of Milling Parameters on Surface Roughness During Milling Kenaf Fibre Reinforced Plastic

Background: Natural fibre is a hairy like raw material which comes from natural sources such as animal, plant and mineral fibres. Kenaf fibre is one of natural fibres which becoming popular as a reinforced for plastic composite material in the industrial application such as aircraft, automotive, sporting goods, and marine engineering. The objectives of this research are to study the effect of milling parameters on the surface roughness in milling kenaf fibre reinforced plastic composite using Taguchi Method. Later the optimization is carried out to determine the optimum condition for the range of milling parameters under investigation in order to minimize the surface roughness (Ra). In this study, Taguchi Method L8 (2 3 ) design is used to conduct a non-sequential experiment. The milling parameters were cutting speed in the range of (V): 500rpm -1000rpm, feed rate (F): 200mm/mim -1200mm/mim, and depth of cut (DOC): 1.00mm -2.00mm. The experimental results were analysed using the Minitab 16 software. It was found that, the optimum parameters for the minimum surface roughness were the cutting speed at 1000 rpm, feed rate at 200mm/min and the depth of cut 1.0 mm. The feed rate and the cutting speed are the main factors that influence the effect of surface roughness in milling kenaf fibre reinforced composite. High cutting speed and low feed rate resulted and low surface roughness for milling kenaf fibre reinforced composite

Mode II fracture toughness of glass–epoxy laminated composites under various heating conditions and strain rates

The high performance of glass fiber reinforced polymer (GFRP) leads this composite to become one of the favourite research topics in engineering. The GFRP is widely used in building structure and other engineering application. In the design of composite structures, the damage-tolerant consideration of composite structure is essential, especially under environmental factor and dynamic effect. Hence, the damage stability of the composite under loadings should be investigated. In this study, the mode II fracture toughness of glass/epoxy laminated composite is evaluated under various strain rates and heating temperatures. The GFRP laminated specimens were fabricated by hand layout method with the heat-treated temperature of 40 �C, 60 �C and 80 �C. The experimental mode II fracture toughness data were obtained from the end-notched flexure (ENF) test method with the strain rate from 1 mm/min to 5 min/min. The experimental results showed that the mode II fracture toughness of the GFRP laminate composite increase with the increase in strain rate. However, the mode II fracture toughness of the GFRP laminate composite is relatively insensitive to heating temperature.

The role of head-up cardiopulmonary resuscitation in sudden cardiac arrest: a systematic review and meta-analysis

BACKGROUND: Head-up cardiopulmonary resuscitation (HU-CPR) is an experimental treatment for sudden cardiac arrest (SCA), where cardiopulmonary resuscitation (CPR) is performed in a ramped position. We evaluated whether HU-CPR improved survival and surrogate outcomes as compared to standard CPR (S-CPR). METHODS: Studies reporting on HU-CPR in SCA were searched for in PubMed, Embase and Cochrane Library from inception to May 1st 2021. Outcomes included neurologically-intact survival, 24-hour-survival, intracranial pressure (ICP), cerebral perfusion pressure (CerPP) and brain blood flow (BBF). Risk of bias was assessed using the GRADE assessment tool and Newcastle Ottawa Scale. Fixed- and random-effects models were used to estimate the pooled effects of HU-CPR at 30 degrees. RESULTS: Thirteen articles met the criteria for inclusion (11 animal-only studies, one before-and-after human-only study, one study that utilized human- and animal-cadavers). Among animal studies, the most common implementation of HU-CPR was a 30-degree upward tilt of the head and thorax (n=7), while four studies investigated controlled sequential elevation (CSE). Two animal studies reported improved cerebral performance category (CPC) scores at 24-hour. The pooled effect on 24-hour survival was not statistically significant (P=0.37). The lone human study reported doubled return of spontaneous circulation (ROSC) (17.9% versus 34.2%, P<0.0001). The pooled effect on ROSC in three porcine studies was OR =3.63 (95% CI: 0.72–18.39). Pooled effects for surrogate physiological outcomes of intracranial cranial pressure (MD −14.08, 95% CI: −23.21 to −4.95, P=0.003), CerPP (MD 14.39, 95% CI: 3.07–25.72, P=0.01) and BBF (MD 0.14, 95% CI: 0.02–0.27, P=0.03), showed statistically significant benefit. DISCUSSION: Overall, HU-CPR improved neurologically-intact survival at 24-hour, ROSC and physiological surrogate outcomes in animal models. Despite promising preclinical data, and one human observational study, clinical equipoise remains surrounding the role of HU-CPR in SCA, necessitating clarification with future randomized human trials

A comparison of the clinical, laboratory and epidemiological features of two divergent subpopulations of Plasmodium knowlesi

Plasmodium knowlesi, a simian malaria parasite responsible for all recent indigenous cases of malaria in Malaysia, infects humans throughout Southeast Asia. There are two genetically distinct subpopulations of Plasmodium knowlesi in Malaysian Borneo, one associated with long-tailed macaques (termed cluster 1) and the other with pig-tailed macaques (cluster 2). A prospective study was conducted to determine whether there were any between-subpopulation differences in clinical and laboratory features, as well as in epidemiological characteristics. Over 2 years, 420 adults admitted to Kapit Hospital, Malaysian Borneo with knowlesi malaria were studied. Infections with each subpopulation resulted in mostly uncomplicated malaria. Severe disease was observed in 35/298 (11.7%) of single cluster 1 and 8/115 (7.0%) of single cluster 2 infections (p = 0.208). There was no clinically significant difference in outcome between the two subpopulations. Cluster 1 infections were more likely to be associated with peri-domestic activities while cluster 2 were associated with interior forest activities consistent with the preferred habitats of the respective macaque hosts. Infections with both P. knowlesi subpopulations cause a wide spectrum of disease including potentially life-threatening complications, with no implications for differential patient management