Displaying publications 1 - 20 of 110 in total

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  1. Jing W, Tao H, Rahman MA, Kabir MN, Yafeng L, Zhang R, et al.
    Work, 2021;68(3):923-934.
    PMID: 33612534 DOI: 10.3233/WOR-203426
    BACKGROUND: Human-Computer Interaction (HCI) is incorporated with a variety of applications for input processing and response actions. Facial recognition systems in workplaces and security systems help to improve the detection and classification of humans based on the vision experienced by the input system.

    OBJECTIVES: In this manuscript, the Robotic Facial Recognition System using the Compound Classifier (RERS-CC) is introduced to improve the recognition rate of human faces. The process is differentiated into classification, detection, and recognition phases that employ principal component analysis based learning. In this learning process, the errors in image processing based on the extracted different features are used for error classification and accuracy improvements.

    RESULTS: The performance of the proposed RERS-CC is validated experimentally using the input image dataset in MATLAB tool. The performance results show that the proposed method improves detection and recognition accuracy with fewer errors and processing time.

    CONCLUSION: The input image is processed with the knowledge of the features and errors that are observed with different orientations and time instances. With the help of matching dataset and the similarity index verification, the proposed method identifies precise human face with augmented true positives and recognition rate.

  2. Zhang G, Jing W, Tao H, Rahman MA, Salih SQ, Al-Saffar A, et al.
    Work, 2021;68(3):935-943.
    PMID: 33612535 DOI: 10.3233/WOR-203427
    BACKGROUND: Human-Robot Interaction (HRI) has become a prominent solution to improve the robustness of real-time service provisioning through assisted functions for day-to-day activities. The application of the robotic system in security services helps to improve the precision of event detection and environmental monitoring with ease.

    OBJECTIVES: This paper discusses activity detection and analysis (ADA) using security robots in workplaces. The application scenario of this method relies on processing image and sensor data for event and activity detection. The events that are detected are classified for its abnormality based on the analysis performed using the sensor and image data operated using a convolution neural network. This method aims to improve the accuracy of detection by mitigating the deviations that are classified in different levels of the convolution process.

    RESULTS: The differences are identified based on independent data correlation and information processing. The performance of the proposed method is verified for the three human activities, such as standing, walking, and running, as detected using the images and sensor dataset.

    CONCLUSION: The results are compared with the existing method for metrics accuracy, classification time, and recall.

  3. Tao H, Rahman MA, Al-Saffar A, Zhang R, Salih SQ, Zain JM, et al.
    Work, 2021;68(3):853-861.
    PMID: 33612528 DOI: 10.3233/WOR-203419
    BACKGROUND: Nowadays, workplace violence is found to be a mental health hazard and considered a crucial topic. The collaboration between robots and humans is increasing with the growth of Industry 4.0. Therefore, the first problem that must be solved is human-machine security. Ensuring the safety of human beings is one of the main aspects of human-robotic interaction. This is not just about preventing collisions within a shared space among human beings and robots; it includes all possible means of harm for an individual, from physical contact to unpleasant or dangerous psychological effects.

    OBJECTIVE: In this paper, Non-linear Adaptive Heuristic Mathematical Model (NAHMM) has been proposed for the prevention of workplace violence using security Human-Robot Collaboration (HRC). Human-Robot Collaboration (HRC) is an area of research with a wide range of up-demands, future scenarios, and potential economic influence. HRC is an interdisciplinary field of research that encompasses cognitive sciences, classical robotics, and psychology.

    RESULTS: The robot can thus make the optimal decision between actions that expose its capabilities to the human being and take the best steps given the knowledge that is currently available to the human being. Further, the ideal policy can be measured carefully under certain observability assumptions.

    CONCLUSION: The system is shown on a collaborative robot and is compared to a state of the art security system. The device is experimentally demonstrated. The new system is being evaluated qualitatively and quantitatively.

  4. Zheyuan C, Rahman MA, Tao H, Liu Y, Pengxuan D, Yaseen ZM
    Work, 2021;68(3):825-834.
    PMID: 33612525 DOI: 10.3233/WOR-203416
    BACKGROUND: The increasing use of robotics in the work of co-workers poses some new problems in terms of occupational safety and health. In the workplace, industrial robots are being used increasingly. During operations such as repairs, unmanageable, adjustment, and set-up, robots can cause serious and fatal injuries to workers. Collaborative robotics recently plays a rising role in the manufacturing filed, warehouses, mining agriculture, and much more in modern industrial environments. This development advances with many benefits, like higher efficiency, increased productivity, and new challenges like new hazards and risks from the elimination of human and robotic barriers.

    OBJECTIVES: In this paper, the Advanced Human-Robot Collaboration Model (AHRCM) approach is to enhance the risk assessment and to make the workplace involving security robots. The robots use perception cameras and generate scene diagrams for semantic depictions of their environment. Furthermore, Artificial Intelligence (AI) and Information and Communication Technology (ICT) have utilized to develop a highly protected security robot based risk management system in the workplace.

    RESULTS: The experimental results show that the proposed AHRCM method achieves high performance in human-robot mutual adaption and reduce the risk.

    CONCLUSION: Through an experiment in the field of human subjects, demonstrated that policies based on the proposed model improved the efficiency of the human-robot team significantly compared with policies assuming complete human-robot adaptation.

  5. Wei H, Rahman MA, Hu X, Zhang L, Guo L, Tao H, et al.
    Work, 2021;68(3):845-852.
    PMID: 33612527 DOI: 10.3233/WOR-203418
    BACKGROUND: The selection of orders is the method of gathering the parts needed to assemble the final products from storage sites. Kitting is the name of a ready-to-use package or a parts kit, flexible robotic systems will significantly help the industry to improve the performance of this activity. In reality, despite some other limitations on the complexity of components and component characteristics, the technological advances in recent years in robotics and artificial intelligence allows the treatment of a wide range of items.

    OBJECTIVE: In this article, we study the robotic kitting system with a Robotic Mounted Rail Arm System (RMRAS), which travels narrowly to choose the elements.

    RESULTS: The objective is to evaluate the efficiency of a robotic kitting system in cycle times through modeling of the elementary kitting operations that the robot performs (pick and room, move, change tools, etc.). The experimental results show that the proposed method enhances the performance and efficiency ratio when compared to other existing methods.

    CONCLUSION: This study with the manufacturer can help him assess the robotic area performance in a given design (layout and picking a policy, etc.) as part of an ongoing project on automation of kitting operations.

  6. Guangnan Z, Tao H, Rahman MA, Yao L, Al-Saffar A, Meng Q, et al.
    Work, 2021;68(3):871-879.
    PMID: 33612530 DOI: 10.3233/WOR-203421
    BACKGROUND: An isolated robot must take account of uncertainty in its world model and adapt its activities to take into account such as uncertainty. In the same way, a robot interaction with security and privacy issues (RISAPI) with people has to account for its confusion about the human internal state, as well as how this state will shift as humans respond to the robot.

    OBJECTIVES: This paper discusses RISAPI of our original work in the field, which shows how probabilistic planning and system theory algorithms in workplace robotic systems that work with people can allow for that reasoning using a security robot system. The problem is a general way as an incomplete knowledge 2-player game.

    RESULTS: In this general framework, the various hypotheses and these contribute to thrilling and complex robot behavior through real-time interaction, which transforms actual human subjects into a spectrum of production systems, robots, and care facilities.

    CONCLUSION: The models of the internal human situation, in which robots can be designed efficiently, are limited, and achieve optimal computational intractability in large, high-dimensional spaces. To achieve this, versatile, lightweight portrayals of the human inner state and modern algorithms offer great hope for reasoning.

  7. Tao H, Rahman MA, Jing W, Li Y, Li J, Al-Saffar A, et al.
    Work, 2021;68(3):903-912.
    PMID: 33720867 DOI: 10.3233/WOR-203424
    BACKGROUND: Human-robot interaction (HRI) is becoming a current research field for providing granular real-time applications and services through physical observation. Robotic systems are designed to handle the roles of humans and assist them through intrinsic sensing and commutative interactions. These systems handle inputs from multiple sources, process them, and deliver reliable responses to the users without delay. Input analysis and processing is the prime concern for the robotic systems to understand and resolve the queries of the users.

    OBJECTIVES: In this manuscript, the Interaction Modeling and Classification Scheme (IMCS) is introduced to improve the accuracy of HRI. This scheme consists of two phases, namely error classification and input mapping. In the error classification process, the input is analyzed for its events and conditional discrepancies to assign appropriate responses in the input mapping phase. The joint process is aided by a linear learning model to analyze the different conditions in the event and input detection.

    RESULTS: The performance of the proposed scheme shows that it is capable of improving the interaction accuracy by reducing the ratio of errors and interaction response by leveraging the information extraction from the discrete and successive human inputs.

    CONCLUSION: The fetched data are analyzed by classifying the errors at the initial stage to achieve reliable responses.

  8. Mansor MS, Sah SA, Koon LC, Rahman MA
    Trop Life Sci Res, 2011 Dec;22(2):65-80.
    PMID: 24575218 MyJurnal
    Bird surveys were conducted in the Padawan Limestone Area for seven days at each of two study sites, Giam and Danu, from August to December 2008. The purpose of the study was to compare the area's bird species richness and abundance of bird species in other limestone areas and in other forest types. The study also compared the species richness and relative abundance of birds in undisturbed and disturbed areas at both study sites. Twenty mist nets were deployed for 12 hours daily. During this study period, direct observations of birds were also made. In all, 80 species from 34 families were recorded at both sites. At Giam, 120 birds were mist-netted. These birds represented 31 species from 16 families. The direct observations at Giam recorded 13 species from 11 families. In the undisturbed area, 21 species from 13 families were mist-netted, whereas in the disturbed area, 21 species from 10 families were mist-netted. In Danu, a total of 48 birds, representing 25 species from 12 families, were mist-netted. The observations at Danu recorded 34 species from 19 families. Twelve species from 7 families were mist-netted in the undisturbed area, whereas 18 species from 11 families were mist-netted in the disturbed area. Statistical analysis showed that the species diversity index differed significantly between undisturbed and disturbed areas.
  9. Rahman LF, Bin Ibne Reaz M, Yin CC, Marufuzzaman M, Rahman MA
    ScientificWorldJournal, 2014;2014:258068.
    PMID: 25114959 DOI: 10.1155/2014/258068
    Circuit intricacy, speed, low-offset voltage, and resolution are essential factors for high-speed applications like analog-to-digital converters (ADCs). The comparator circuit with preamplifier increases the power dissipation, as it requires higher amount of currents than the latch circuitry. In this research, a novel topology of dynamic latch comparator is illustrated, which is able to provide high speed, low offset, and high resolution. Moreover, the circuit is able to reduce the power dissipation as the topology is based on latch circuitry. The cross-coupled circuit mechanism with the regenerative latch is employed for enhancing the dynamic latch comparator performance. In addition, input-tracking phase is used to reduce the offset voltage. The Monte-Carlo simulation results for the designed comparator in 0.18 μm CMOS process show that the equivalent input-referred offset voltage is 720 μV with 3.44 mV standard deviation. The simulated result shows that the designed comparator has 8-bit resolution and dissipates 158.5 μW of power under 1.8 V supply while operating with a clock frequency of 50 MHz. In addition, the proposed dynamic latch comparator has a layout size of 148.80 μm × 59.70 μm.
  10. Rahman MA, Yusoff FM, Arshad A, Uehara T
    ScientificWorldJournal, 2014;2014:918028.
    PMID: 24624048 DOI: 10.1155/2014/918028
    We report here, the effects of extended competency on larval survival, metamorphosis, and postlarval juvenile growth of four closely related species of tropical sea urchins, Echinometra sp. A (Ea), E. mathaei (Em), Echinometra sp. C (Ec), and E. oblonga (Eo). Planktotrophic larvae of all four species fed on cultured phytoplankton (Chaetoceros gracilis) attained metamorphic competence within 22-24 days after fertilization. Competent larvae were forced to delay metamorphosis for up to 5 months by preventing them from settling in culture bottles with continuous stirring on a set of 10 rpm rotating rollers and larval survival per monthly intervals was recorded. Larval survival was highest at 24 days, when competence was attained (0 delayed period), and there were no significant differences among the four species. Larvae that had experienced a prolonged delay had reduced survival rate, metamorphosis success, and juvenile survival, but among older larvae, Em had the highest success followed by Ea, Eo, and Ec. Juveniles from larvae of all four species that metamorphosed soon after becoming competent tended to have higher growth rates (test diameter and length of spines) than juveniles from larvae that metamorphosed after a prolonged period of competence with progressively slower growth the longer the prolonged period. Despite the adverse effects of delaying metamorphosis on growth parameters, competent larvae of all four species were able to survive up to 5 months and after metamorphosis grew into 1-month-old juveniles in lab condition. Overall, delayed larvae of Em showed significantly higher larval survival, metamorphosis, and juvenile survival than Ea and Eo, while Ec showed the lowest values in these performances. Em has the most widespread distribution of these species ranging from Africa to Hawaii, while Ec probably has the most restricted distribution. Consequently, differences in distribution may be related to differences in the ability to delay metamorphosis.
  11. Rahman MA, Yusoff FM, Arshad A, Shamsudin MN, Amin SM
    ScientificWorldJournal, 2012;2012:938482.
    PMID: 23055824 DOI: 10.1100/2012/938482
    Salmacis sphaeroides (Linnaeus, 1758) is one of the regular echinoids, occuring in the warm Indo-West Pacific, including Johor Straits, between Malaysia and Singapore. In order to investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of S. sphaeroides in laboratory condition. Gametes were obtained from adult individuals by 0.5 M KCl injection into the coelomic cavity. Fertilization rate at limited sperm concentration (10(-5) dilution) was 96.6 ± 1.4% and the resulting embryos were reared at 24°C. First cleavage (2-cell), 4-cell, 8-cell, 16-cell, 32-cell, and multicell (Morulla) stages were achieved 01.12, 02.03, 02.28, 02.51, 03.12, and 03.32 h postfertilization. Ciliated blastulae with a mean length of 174.72 ± 4.43 μm hatched 08.45 h after sperm entry. The gastrulae formed 16.15 h postfertilization and the archenteron elongated constantly while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larva started to feed unicellular algae in 2 d, grew continuously, and finally attained metamorphic competence in 35 d after fertilization. Metamorphosis took approximately 1 h 30 min from attachment to the complete resorption of larval tissues and the development of complete juvenile structure with adult spines, extended tubefeet and well-developed pedicellaria, the whole event of which usually took place within 1 d postsettlement. This study represents the first successful investigation on embryonic, larval, and early juvenile development of S. sphaeroides. The findings would greatly be helpful towards the understanding of ontogeny and life-history strategies, which will facilitate us to develop the breeding, seed production, and culture techniques of sea urchins in captive condition.
  12. Chandraseharan P, Sockalingam SNM, Shafiei Z, Zakaria ASI, Mahyuddin A, Rahman MA
    J Contemp Dent Pract, 2023 Oct 01;24(10):779-786.
    PMID: 38152911 DOI: 10.5005/jp-journals-10024-3581
    AIMS AND BACKGROUND: This study evaluates the antimicrobial activities of commercially available 5% apple cider vinegar (ACV) against Enterococcus faecalis, Streptococcus mutans, and Lactobacillus casei. Materials and methods: Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were conducted using the broth microdilution method. Sodium hypochlorite (NaOCl) of 5.25% was used as a positive control, and comparisons were also made with acetic acid (AA) as the main ingredient in ACV. The three test bacteria treated with the most effective ACV dilution were visualized under a transmission electron microscope (TEM) for structural changes.

    RESULTS: Minimal inhibitory concentration was determined at 0.625% of the concentration of ACV against S. mutans and E. faecalis and 1.25% of the concentration of ACV against L. casei with two-fold serial dilutions. A concentration of 5 × 10-1% with 10-fold serial dilutions was found to be the MIC value for all three bacteria. No significant differences were found when compared with the positive control (NaOCl) (p = 0.182, p = 0.171, and p = 0.234), respectively, for two-fold serial dilutions and (p = 1.000, p = 0.658, and p = 0.110), respectively for 10-fold serial dilutions. MBC was observed to be 5% ACV for both E. faecalis and S. mutans. However, positive microbial growth was observed on the agar plate when cultured with L. casei. An independent sample t-test showed no significant differences (p > 0.05) in the antimicrobial activities between 5% ACV and 5% pure AA. TEM revealed cell wall and cytoplasmic membrane disruptions on all three bacteria at MIC value.

    CONCLUSION: Apple cider vinegar has antimicrobial activities against Enterococcus faecalis, Streptococcus mutans, and Lactobacillus casei at their respective MIC values.

    CLINICAL SIGNIFICANCE: Apple cider vinegar can be an alternative antimicrobial dental pulp disinfectant to sodium hypochlorite. Apple cider vinegar can be used safely, especially in children's dental pulp therapy and deep caries management, when adequate tooth isolation is not readily achievable. Thus, adverse reactions commonly associated with other frequently used chemical disinfectants can be avoided.

  13. Maniam T, Rahman MA
    Med J Malaysia, 1994 Sep;49(3):252-4.
    PMID: 7845275
    Creatine kinase (CK) is an enzyme that is found widely in muscle tissues. Raised levels would occur when there is muscle damage. Raised levels are used as one of the diagnostic criteria for Neuroleptic Malignant Syndrome (NMS). This study looks at CK levels in 30 psychotic inpatients without NMS and compares them with 10 patients with NMS. It was found that 67% of the patients without NMS had raised CK levels, 20% of whom had levels in excess of 1000 IU/L. The rest had a two to five-fold increase over normal limits. Raised levels were associated with the use of intramuscular injections and physical restraints, situations which are well known to result in muscle injury. All the NMS patients had raised CK levels but 40% had levels below 1000 IU/L. Our findings support the idea that CK levels, though helpful, should be interpreted with care as raised levels are nonspecific.
  14. Imada T, Abdul Rahman MA, Kashiwazaki Y, Tanimura N, Syed Hassan S, Jamaluddin A
    J Vet Med Sci, 2004 Jan;66(1):81-3.
    PMID: 14960818
    Eight clones of monoclonal antibodies (Mabs) to Nipah virus (NV) were produced against formalin-inactivated NV antigens. They reacted positive by indirect immunofluorescent antibody test, and one of them also demonstrated virus neutralizing activity. They were classified into six different types based on their biological properties. These Mabs will be useful for immunodiagnosis of NV infections in animals and further research studies involving the genomes and proteins of NV.
  15. Dahlan HM, Karsani SA, Rahman MA, Hamid NA, Top AG, Ngah WZ
    J Nutr Biochem, 2012 Jul;23(7):741-51.
    PMID: 21840697 DOI: 10.1016/j.jnutbio.2011.03.018
    Vitamin E has been suggested to modulate age-associated changes by altering the redox balance resulting in altered gene and/or protein expression. Here we have utilized proteomics to determine whether such regulation in protein expression occurs in human lymphocytes from two different age groups stressed with H₂O₂ and then treated with vitamin E in the form of tocotrienol-rich fraction (TRF). In this study, lymphocytes obtained from young (30-49 years old) and old (>50 years old) volunteers were first challenged with 1 mM H₂O₂. They were then treated by exposure to 50, 100 and 200 μg/ml TRF. Two-dimensional gel electrophoresis followed by MALDI-TOF/TOF (matrix-assisted laser desorption/ionization time-of-flight/time-of-flight) tandem mass spectrometry was then performed on whole-cell protein extracts to identify proteins that have changed in expression. A total of 24 proteins were found to be affected by H₂O₂ and/or TRF treatment. These included proteins that were related to metabolism, antioxidants, structural proteins, protein degradation and signal transduction. Of particular interest was the regulation of a number of proteins involved in stress response--peroxiredoxin-2, peroxiredoxin-3 and peroxiredoxin-6-all of which were shown to be down-regulated with H₂O₂ exposure. The effect was reversed following TRF treatment. The expression of peroxiredoxin-2 and peroxiredoxin-6 was confirmed by quantitative reverse transcriptase polymerase chain reaction. These results suggested that TRF directly influenced the expression dynamics of the peroxiredoxin-2, thus improving the cells ability to resist damage caused by oxidative stress.
  16. Rahman MA, Zaman N, Asyhari AT, Al-Turjman F, Alam Bhuiyan MZ, Zolkipli MF
    Sustain Cities Soc, 2020 Nov;62:102372.
    PMID: 32834935 DOI: 10.1016/j.scs.2020.102372
    The COVID-19 disease has once again reiterated the impact of pandemics beyond a biomedical event with potential rapid, dramatic, sweeping disruptions to the management, and conduct of everyday life. Not only the rate and pattern of contagion that threaten our sense of healthy living but also the safety measures put in place for containing the spread of the virus may require social distancing. Three different measures to counteract this pandemic situation have emerged, namely: (i) vaccination, (ii) herd immunity development, and (iii) lockdown. As the first measure is not ready at this stage and the second measure is largely considered unreasonable on the account of the gigantic number of fatalities, a vast majority of countries have practiced the third option despite having a potentially immense adverse economic impact. To mitigate such an impact, this paper proposes a data-driven dynamic clustering framework for moderating the adverse economic impact of COVID-19 flare-up. Through an intelligent fusion of healthcare and simulated mobility data, we model lockdown as a clustering problem and design a dynamic clustering algorithm for localized lockdown by taking into account the pandemic, economic and mobility aspects. We then validate the proposed algorithms by conducting extensive simulations using the Malaysian context as a case study. The findings signify the promises of dynamic clustering for lockdown coverage reduction, reduced economic loss, and military unit deployment reduction, as well as assess potential impact of uncooperative civilians on the contamination rate. The outcome of this work is anticipated to pave a way for significantly reducing the severe economic impact of the COVID-19 spreading. Moreover, the idea can be exploited for potentially the next waves of corona virus-related diseases and other upcoming viral life-threatening calamities.
  17. Alyan E, Saad NM, Kamel N, Yusoff MZ, Zakariya MA, Rahman MA, et al.
    Sensors (Basel), 2021 Mar 11;21(6).
    PMID: 33799722 DOI: 10.3390/s21061968
    This study aims to investigate the effects of workplace noise on neural activity and alpha asymmetries of the prefrontal cortex (PFC) during mental stress conditions. Workplace noise exposure is a pervasive environmental pollutant and is negatively linked to cognitive effects and selective attention. Generally, the stress theory is assumed to underlie the impact of noise on health. Evidence for the impacts of workplace noise on mental stress is lacking. Fifteen healthy volunteer subjects performed the Montreal imaging stress task in quiet and noisy workplaces while their brain activity was recorded using electroencephalography. The salivary alpha-amylase (sAA) was measured before and immediately after each tested workplace to evaluate the stress level. The results showed a decrease in alpha rhythms, or an increase in cortical activity, of the PFC for all participants at the noisy workplace. Further analysis of alpha asymmetry revealed a greater significant relative right frontal activation of the noisy workplace group at electrode pairs F4-F3 but not F8-F7. Furthermore, a significant increase in sAA activity was observed in all participants at the noisy workplace, demonstrating the presence of stress. The findings provide critical information on the effects of workplace noise-related stress that might be neglected during mental stress evaluations.
  18. Nazmi N, Abdul Rahman MA, Yamamoto S, Ahmad SA, Zamzuri H, Mazlan SA
    Sensors (Basel), 2016 Aug 17;16(8).
    PMID: 27548165 DOI: 10.3390/s16081304
    In recent years, there has been major interest in the exposure to physical therapy during rehabilitation. Several publications have demonstrated its usefulness in clinical/medical and human machine interface (HMI) applications. An automated system will guide the user to perform the training during rehabilitation independently. Advances in engineering have extended electromyography (EMG) beyond the traditional diagnostic applications to also include applications in diverse areas such as movement analysis. This paper gives an overview of the numerous methods available to recognize motion patterns of EMG signals for both isotonic and isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who would like to select the most appropriate methodology in classifying motion patterns, especially during different types of contractions. For feature extraction, the probability density function (PDF) of EMG signals will be the main interest of this study. Following that, a brief explanation of the different methods for pre-processing, feature extraction and classifying EMG signals will be compared in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above.
  19. Rahman MA, Ahamed E, Faruque MRI, Islam MT
    Sci Rep, 2018 Oct 08;8(1):14948.
    PMID: 30297730 DOI: 10.1038/s41598-018-33295-0
    Various techniques are commonly used to produce nano-crystalline NiAl2O4 materials; however, their practical applications in the microwave region remain very limited. In this work, flexible substrates for metamaterials containing two different concentrations of NiAl2O4 (labelled Ni36 and Ni42) have been synthesised using a sol-gel method. The formation of spinel structures in the synthesised materials is confirmed, and their crystalline sizes are determined using scanning electron microscopy, X-ray diffraction, and energy dispersive X-ray techniques. The dielectric properties, conductivities, loss tangents, and other parameters of the NiAl2O4-based substrates are analysed to evaluate their applicability as dielectric materials for the microwave frequency range. The obtained results show that the fabricated Ni36 and Ni42 nickel aluminates possess dielectric constants of 4.94 and 4.97 and loss tangents of 0.01 and 0.007, respectively; in addition, they exhibit high flexibility and light weight, which make them suitable for applications as metamaterial substrates. The synthesised structures are also validated experimentally using a commercially available electromagnetic simulator; as a result, double negative behaviour of the flexible metamaterials has been observed. Furthermore, it is found that the prepared NiAl2O4 substrates can be used in the S-, C-, and X-bands of the microwave frequency region.
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