Apparent stress-strain relationships in experimental equipment where magnetorheological fluids operate under compression mode

Abstract: This paper presents an experimental investigation of two different magnetorheological ( MR) fluids, namely, water-based and hydrocarbon-based MR fluids in compression mode under various applied currents. Finite element method magnetics was used to predict the magnetic field distribution inside the MR fluids generated by a coil. A test rig was constructed where the MR fluid was sandwiched between two flat surfaces. During the compression, the upper surface was moved towards the lower surface in a vertical direction. Stress-strain relationships were obtained for arrangements of equipment where each type of fluid was involved, using compression test equipment. The apparent compressive stress was found to be increased with the increase in magnetic field strength. In addition, the apparent compressive stress of the water-based MR fluid showed a response to the compressive strain of greater magnitude. However, during the compression process, the hydrocarbon-based MR fluid appeared to show a unique behaviour where an abrupt pressure drop was discovered in a region where the apparent compressive stress would be expected to increase steadily. The conclusion is drawn that the apparent compressive stress of MR fluids is influenced strongly by the nature of the carrier fluid and by the magnitude of the applied current

Solvent dependence of the rheological properties in hydrogel magnetorheological plastomer

Chemically crosslinked hydrogel magnetorheological (MR) plastomer (MRP) embedded with carbonyl iron particles (CIPs) exhibits excellent magnetic performance (MR effect) in the presence of external stimuli especially magnetic field. However, oxidation and desiccation in hydrogel MRP due to a large amount of water content as a dispersing phase would limit its usage for long‐term applications, especially in industrial engineering. In this study, different solvents such as dimethyl sulfoxide (DMSO) are also used to prepare polyvinyl alcohol (PVA) hydrogel MRP. Thus, to understand the dynamic viscoelastic properties of hydrogel MRP, three different samples with different solvents: water, DMSO, and their binary mixtures (DMSO/water) were prepared and systematically carried out using the oscillatory shear. The outcomes demonstrate that the PVA hydrogel MRP prepared from precursor gel with water shows the highest MR effect of 15,544% among the PVA hydrogel MRPs. However, the samples exhibit less stability and tend to oxidise after a month. Meanwhile, the samples with binary mixtures (DMSO/water) show an acceptable MR effect of 11,024% with good stability and no CIPs oxidation. Otherwise, the sample with DMSO has the lowest MR effect of 7049% and less stable compared to the binary solvent samples. This confirms that the utilisation of DMSO as a new solvent affects the rheological properties and stability of the samples

The epifaunal marine bivalves and macrophytes in Merambong Shoal, Pulai River Estuary, Straits of Malacca

The study was carried out to investigate the diversity of epifaunal bivalves in Merambong seagrass bed, Pulai River Estuary. The sample collection field trips started from May 2008 to July 2009, 18 transects (from six stations) have been laid perpendicularly along the elongated shoal during lowest low spring tide. A total of 15 species from 10 bivalve families were recorded throughout the study period. Young Anadara gubernaculum attached to Enhalus ecoroides showed the highest abundance throughout the seagrass bed. Veneridae is the most diverse family with four species recorded during the study followed by 2 species each for Mytilidae and Pinnidae. Negative correlation was observed between Circe scripta abundance and Ulva spp. coverage (r 2 =-0.829, P= 0.042). Station 4 (H'=1.2137; 1-D=0.5807; S=10) and Station 6 (H'=1.5279; 1-D=0.6696; S=13) have higher bivalve diversity and species richness, and are more heterogeneous compared to other stations. However, bivalve density was relatively lower in both stations 4 and 6 than the rest of the stations. The result of this study revealed that the coverage of macrophytes plays an important role in determining the density and distribution of epifaunal bivalves

Rheological and resistance properties of magnetorheological elastomer with cobalt for sensor application

Cobalt particles have been introduced as a filler due to the advantages of embedding their magnetic and electrical properties in magnetorheological elastomer (MRE). In the present research, the rheology and resistance of MRE are experimentally evaluated. Isotropic and anisotropic MRE samples containing silicone rubber and cobalt particles were fabricated. The magnetic properties of MRE are conducted using a vibrating sample magnetometer (VSM). The morphological aspects of MRE are observed by using field emission scanning electron microscopy (FESEM) and characterized by energy-dispersive X-ray spectroscopy (EDX). Rheological properties under various magnetic field strengths were measured for the magnetic field, strain amplitude, and frequency sweep test by using a parallel-plate rheometer. Subsequently, the resistance of MRE is tested under different applied forces and magnetic fields. The MRE storage modulus depicted an enhancement in field-dependent modulus across all the applied magnetic fields. The electrical resistance generated from the sample can be manipulated by external magnetic fields and mechanical loads. The conductivity of MRE is due to the existence of cobalt arrangements observed by FESEM. By introducing cobalt as filler and obtaining satisfactory results, the study might open new avenues for cobalt to be used as filler in MRE fabrication for future sensing applications

Microaneurysms Segmentation in Retinal Images for Early Detection of Diabetic Retinopathy

Microaneurysms (MAs) are the tiny aneurysms which show the earliest sign of diabetic retinopathy (DR). MAs might progress and harm human eyes if not treated. This paper presents an automatic method for segmentation of MAs in order to control the progression of DR. MESSIDOR database of 40 random images were utilised for further processing. The proposed approach covered pre-processing steps, contrast enhancement, filtration and segmentation by h-maxima transform and multilevel thresholding. Some post-processing techniques also involved in this approach using morphological operation. The detected MAs determined the grade of disease severity. The result showed that the percentage of severity disease detected was 60%

Construction procurement in industrialised building system

The government, through CIDB Malaysia have continuously promoting Industrialised Building System (IBS) to increase the immense efficiency of the building performance structure. However, the level of IBS adoption among the construction players in Malaysia is still low and far from the government expectation. It is evident that most of the IBS projects developments in Malaysia are still conducted by using the conventional procurement method. This creates a number of issues such as reworks, time delay, rising cost, lack of communication and integration problem. Thus, this paper will identify existing procurement process used for IBS projects in Malaysia construction industry. Identifying existing procurement process helps in providing significant elements before creation of a more effective new procurement for IBS projects in Malaysia. Expert interviews was used, whereby 5 (five) interviews sessions were conducted with IBS experts in Malaysia construction industry. Thematic analysis was utilised to analyse the interview result by identifying the existing procurement process adopted in current IBS projects. Findings from expert interviews showed that there are three different procurement process commonly applied in current IBS projects. Result also shown that one of the significant barriers to IBS adoption is the current practice of procurement and team integration. Therefore, a more effective new procurement for IBS projects should be considered and pursued urgently in order to improve IBS implementation in the Malaysian construction industry

Preliminary results of electrical characterization of GO towards MCF7 and MCF10a at different concentrations

GO is the 2D carbon sheet with additional functional groups, is more stable in various solvents, easy to be produced and manipulated especially in biological system. At the moment, GO is only utilized as the drug delivery agent during treatment. In this study, the resistivity of GO towards breast cancer cell (MCF7) and normal breast cell (MCF10a) using interdigitated electrodes (IDE) were investigated. The interaction of different concentrations of GO as the sensing material on the tested cells which act as analyte can change electrical response. The tested cell were treated with six different concentrations of GO and was dropped to the IDE with different period of time in order to examine electrical behavior. For MCF10a, at high concentration the resistances of MCF10 remain in the same order of magnitude with increasing time of detection while for MCF7 at high concentration, the resistances were greatly influenced by the time of detection where the value significantly changed after 5 minutes and 10 minutes. The number of viable cell does not give effect to the resistance

Smart home aquaponic system monitoring and control with internet of things using mobile application

Food security has been a recurrent concern for numerous nations, including Malaysia. Climate change and population growth exacerbate this issue by increasing necessity food. In past few years, aquaponics has proven beneficial for fish and plant production, based on the idea that if every household can generate its own fish and plants, the nation's overall food consumption will reduce. The suggested smart house aquaponics system comprises an assortment of internet-connected sensors, actuators, and ESP32 microcontrollers that continuously monitor, adjust, and record the water and air quality of the fish tank. The Internet of Things (IoT) mobile application feature can alert the user in the event of an abnormal system state in terms of maintaining the health and growth of fish and plants. The Internet of Things (IoT) mobile application feature can alert the user in the event of an abnormal system state in terms of maintaining the health and growth of fish and plants. When the pH and turbidity thresholds are surpassed, the pumps are actuated to either fill or drain the tank. The results show that the design for a smart aquaponics system that can be used in a home is able to monitor and control all the parameters that are needed to cultivate wholesome fish and vegetation

Improving Vehicle Ride and Handling Using LQG CNF Fusion Control Strategy for an Active Antiroll Bar System

This paper analyses a comparison of performance for an active antiroll bar (ARB) system using two types of control strategy. First of all, the LQG control strategy is investigated and then a novel LQG CNF fusion control method is developed to improve the performances on vehicle ride and handling for an active antiroll bar system. However, the ARB system has to balance the trade-off between ride and handling performance, where the CNF consists of a linear feedback law and a nonlinear feedback law. Typically, the linear feedback is designed to yield a quick response at the initial stage, while the nonlinear feedback law is used to smooth out overshoots in the system output when it approaches the target reference. The half car model is combined with a linear single track model with roll dynamics which are used for the analysis and simulation of ride and handling. The performances of the control strategies are compared and the simulation results show the LQG CNF fusion improves the performances in vehicle ride and handling

A comparative work on the magnetic field-dependent properties of plate-like and spherical iron particle-based magnetorheological grease

In this study, a new magnetorheological (MR) grease was made featuring plate-like carbonyl iron (CI) particles, and its magnetic field-dependent rheological properties were experimentally characterized. The plate-like CI particles were prepared through high-energy ball milling of spherical CI particles. Then, three different ratios of the CI particles in the MR grease, varying from 30 to 70 wt% were mixed by dispersing the plate-like CI particles into the grease medium with a mechanical stirrer. The magnetic field-dependent rheological properties of the plate-like CI particle-based MR grease were then investigated using a rheometer by changing the magnetic field intensity from 0 to 0.7 T at room temperature. The measurement was undertaken at two different modes, namely, a continuous shear mode and oscillation mode. It was shown that both the apparent viscosity and storage modulus of the MR grease were heavily dependent on the magnetic field intensity as well as the CI particle fraction. In addition, the differences in the yield stress and the MR effect between the proposed MR grease featuring the plate-like CI particles and the existing MR grease with the spherical CI particles were investigated and discussed in detail