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Diagnosis of diabetic retinopathy: automatic extraction of optic disc and exudates from retinal images using marker-controlled watershed transformation

Reza AW, Eswaran C, Dimyati K

J Med Syst, 2011 Dec;35(6):1491-501.
PMID: 20703768 DOI: 10.1007/s10916-009-9426-y

Due to increasing number of diabetic retinopathy cases, ophthalmologists are experiencing serious problem to automatically extract the features from the retinal images. Optic disc (OD), exudates, and cotton wool spots are the main features of fundus images which are used for diagnosing eye diseases, such as diabetic retinopathy and glaucoma. In this paper, a new algorithm for the extraction of these bright objects from fundus images based on marker-controlled watershed segmentation is presented. The proposed algorithm makes use of average filtering and contrast adjustment as preprocessing steps. The concept of the markers is used to modify the gradient before the watershed transformation is applied. The performance of the proposed algorithm is evaluated using the test images of STARE and DRIVE databases. It is shown that the proposed method can yield an average sensitivity value of about 95%, which is comparable to those obtained by the known methods.
Fulltext A new SIR-based sigmoid power control game in cognitive radio networks

Al-Gumaei YA, Noordin KA, Reza AW, Dimyati K

PLoS One, 2014;9(10):e109077.
PMID: 25286044 DOI: 10.1371/journal.pone.0109077

Interference resulting from Cognitive Radios (CRs) is the most important aspect of cognitive radio networks that leads to degradation in Quality of Service (QoS) in both primary and CR systems. Power control is one of the efficient techniques that can be used to reduce interference and satisfy the Signal-to-Interference Ratio (SIR) constraint among CRs. This paper proposes a new distributed power control algorithm based on game theory approach in cognitive radio networks. The proposal focuses on the channel status of cognitive radio users to improve system performance. A new cost function for SIR-based power control via a sigmoid weighting factor is introduced. The existence of Nash Equilibrium and convergence of the algorithm are also proved. The advantage of the proposed algorithm is the possibility to utilize and implement it in a distributed manner. Simulation results show considerable savings on Nash Equilibrium power compared to relevant algorithms while reduction in achieved SIR is insignificant.
Fulltext A new blood vessel extraction technique using edge enhancement and object classification

Badsha S, Reza AW, Tan KG, Dimyati K

J Digit Imaging, 2013 Dec;26(6):1107-15.
PMID: 23515843 DOI: 10.1007/s10278-013-9585-8

Diabetic retinopathy (DR) is increasing progressively pushing the demand of automatic extraction and classification of severity of diseases. Blood vessel extraction from the fundus image is a vital and challenging task. Therefore, this paper presents a new, computationally simple, and automatic method to extract the retinal blood vessel. The proposed method comprises several basic image processing techniques, namely edge enhancement by standard template, noise removal, thresholding, morphological operation, and object classification. The proposed method has been tested on a set of retinal images. The retinal images were collected from the DRIVE database and we have employed robust performance analysis to evaluate the accuracy. The results obtained from this study reveal that the proposed method offers an average accuracy of about 97 %, sensitivity of 99 %, specificity of 86 %, and predictive value of 98 %, which is superior to various well-known techniques.
Fulltext A novel utility function for energy-efficient power control game in cognitive radio networks

Al-Gumaei YA, Noordin KA, Reza AW, Dimyati K

PLoS One, 2015;10(8):e0135137.
PMID: 26258522 DOI: 10.1371/journal.pone.0135137

Spectrum scarcity is a major challenge in wireless communications systems requiring efficient usage and utilization. Cognitive radio network (CRN) is found as a promising technique to solve this problem of spectrum scarcity. It allows licensed and unlicensed users to share the same licensed spectrum band. Interference resulting from cognitive radios (CRs) has undesirable effects on quality of service (QoS) of both licensed and unlicensed systems where it causes degradation in received signal-to-noise ratio (SIR) of users. Power control is one of the most important techniques that can be used to mitigate interference and guarantee QoS in both systems. In this paper, we develop a new approach of a distributed power control for CRN based on utility and pricing. QoS of CR user is presented as a utility function via pricing and a distributed power control as a non-cooperative game in which users maximize their net utility (utility-price). We define the price as a real function of transmit power to increase pricing charge of the farthest CR users. We prove that the power control game proposed in this study has Nash Equilibrium as well as it is unique. The obtained results show that the proposed power control algorithm based on a new utility function has a significant reduction in transmit power consumption and high improvement in speed of convergence.
Fulltext Indonesia as a legal welfare state: A prophetic-transcendental basis

Dimyati K, Nashir H, Elviandri E, Absori A, Wardiono K, Budiono A

Heliyon, 2021 Aug;7(8):e07865.
PMID: 34485743 DOI: 10.1016/j.heliyon.2021.e07865

Introduction: The modern welfare state concept is based on individualistic and liberal social contracts that prioritize individual interests with liberalist, partial and non-holistic hegemonies. The welfare state concept has failed in directing citizens to achieve justice, peace, and welfare. The basic aim of the Republic of Indonesia's formation is to form a welfare country. But the Indonesian constitutional articles do not have the power to form a welfare society compared to those of other states, such as Norway, Japan, the USA, and Malaysia, whose constitutions aim to achieve welfare.
Objective: This research aims to explore the formulation of Indonesia as the Prophetic Transcendental-Based Legal Welfare State. The urgency of this research is on the effort of model invention, or a new postulate on the form of the Indonesian Legal Welfare State.
Methods: This is normative-juridical research with a philosophical approach to find and explore the formulation of Indonesia as the Prophetic Transcendental-Based Legal Welfare State.
Conclusion: This research found that as a Legal Welfare State, Indonesia inspirits Pancasila as the moral-spiritual guidance in all developmental policies on the national law, economy, politics, and culture. Thus, the direction of the state's development is inseparable from its roots, namely the prophetic and transcendental Pancasila.
Novelty: The previous researches discussed Indonesia as a welfare state only based on the determining legislation or laws. But this research discusses the philosophical aspect based on the thoughts of Indonesia's founding fathers.
S-band multiwavelength Brillouin/Raman distributed Bragg reflector fiber lasers

Zulkifli MZ, Ahmad H, Taib JM, Muhammad FD, Dimyati K, Harun SW

Appl Opt, 2013 Jun 1;52(16):3753-6.
PMID: 23736330 DOI: 10.1364/AO.52.003753

A multiwavelength Brillouin/Raman distributed Bragg reflector fiber laser operating in the S-band region is proposed and demonstrated. The laser uses a 7.7 km long dispersion-shifted fiber with an effective mode area of 15 μm(2) as the Brillouin and Raman gain media simultaneously. Two 1420 nm laser diodes with a combined power of 372 mW are used as pump sources, while a fiber Bragg grating with a center wavelength of 1500 nm is used as a reflector in the cavity. The setup is capable of generating 6 clearly defined Stokes lines at the highest pump power, spanning from 1499.8 to 1500.3 nm with the even Stokes having relatively higher peak powers, between 1.4 and 3.5 dBm as compared to the odd Stokes, which have peak powers between -4.7 and -5.0 dBm. The output of the laser is very stable and shows little to no fluctuations over a monitoring period of 50 min.
Domain-wall dark pulse generation with SMF-GIMF-SMF structure as artificial saturable absorber

Chen Y, Cheak TZ, Jin TS, Vinitha G, Dimyati K, Harun SW

Sci Rep, 2024 Jan 25;14(1):2141.
PMID: 38273021 DOI: 10.1038/s41598-024-52640-0

We experimentally demonstrated the generation of domain-wall dark pulse in an Erbium-doped fiber laser using the combination of a 10 cm graded index multimode fiber sandwiched by single mode fibers as artificial saturable absorber. The interaction of phase difference in grade index multimode fiber allowed the stable dual-wavelength oscillation in the cavity. The dual-wavelength centered at 1567.2 nm and 1569.4 nm produces the topological defect in temporal domain and achieved a dark pulse formation with repetition rate of 21.5 MHz. The highest average pulse energy is calculated as 769.6 pJ with pulse width of 5 ns. Throughout the operating pump power range, the average pulse energy and output power increase linearly, with R2 of 0.9999 and achieved the laser efficiency of 9.33%. From the measurement in frequency domain, the signal-to-noise ratio is measured as 49 dB. As compared to reported DW dark pulse works, the proposed structure only required a short length of multimode fiber, which allowed the domain-wall dark pulse to achieve higher pulse repetition rate. The venture of domain wall dark pulse is potentially to pave the foundation toward sustainable industrial growth.
Mode-locked thulium-bismuth codoped fiber laser using graphene saturable absorber in ring cavity

Zen DI, Saidin N, Damanhuri SS, Harun SW, Ahmad H, Ismail MA, et al.

Appl Opt, 2013 Feb 20;52(6):1226-9.
PMID: 23434993 DOI: 10.1364/AO.52.001226

We demonstrate mode locking of a thulium-bismuth codoped fiber laser (TBFL) operating at 1901.6 nm, using a graphene-based saturable absorber (SA). In this work, a single layer graphene is mechanically exfoliated using the scotch tape method and directly transferred onto the surface of a fiber pigtail to fabricate the SA. The obtained Raman spectrum characteristic indicates that the graphene on the core surface has a single layer. At 1552 nm pump power of 869 mW, the mode-locked TBFL self starts to generate an optical pulse train with a repetition rate of 16.7 MHz and pulse width of 0.37 ps. This is a simple, low-cost, stable, and convenient laser oscillator for applications where eye-safe and low-photon-energy light sources are required, such as sensing and biomedical diagnostics.