Hydrothermal assisted synthesis of titanium dioxide nanoparticles modified graphene with enhanced photocatalytic performance

Rahmat Hidayat,Rahmat Hidayat,Tawfik A. Saleh 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.113 No.-

Water purification is a global issue, and most traditional methods have several drawbacks. As a result,new methods and materials must be devised to address the problem of water filtration. The hydrophobicTiO2-ZnO/rGO has been synthesized via single-step hydrothermal methods for the efficiency and effectiveindigo carmine (IC) solution degradation. The characterization of hydrophobic TiO2-ZnO/rGO has shownthat the material has a high contact angle value of around 103.6. Several photocatalytic parameters, pHof IC solution, the dosage of catalyst, and light intensity, were optimized for obtaining the highest degradationefficiency. The results of the photocatalytic study showed that the IC dye degradation process wascontrolled by superoxide anion radical (O2 radicals) to produce more specific products. Modificationswith hydrophobic compounds such as hexamethyldisilizane (HDMS) showed that they could increasethe photocatalytic properties and reusability of the material with a degradation percentage value of upto 95% with a constant rate of 0.0361 min1. Based on these results, this material has the potential tobe further developed for micro and complex photodegradation and self-cleaning materials.

Fuzzy Logic Application in Fault Diagnosis of Transformers Using Dissolved Gases

Rahmat-Allah Hooshmand,Mahdi Banejad 대한전기학회 2008 Journal of Electrical Engineering & Technology Vol.3 No.3

One of the problems with the fault diagnosis of transformers based on dissolved gas is the inability to match the result of the different standards of fault diagnosis with real world standards. In this paper, the results of the different standards are analyzed using fuzzy logic and then compared with the empirical test. The proposed method is based on the standards and guidelines of the International Electrotechnical Commission (IEC), the Central Electric Generating Board (CEGB), and the American Society for Testing and Material (ASTM) and its main task is to assist the conventional gas ratio method. The comparison between the suggested method and existing methods indicates the capability of the suggested method in the on-line fault diagnosis of transformers, In addition, in some cases the existing standards are not able to diagnose the fault. For theses instances, the presented method has the potential of diagnosing the fault. In this paper, the information of three real transformers is used to show the capability of the suggested method in diagnosing the fault. The results validate the capability of the presented method in fault diagnosis of the transformer.

Development of a novel ozone gas sensor based on sol-gel fabricated photonic crystal

Rahmat, M.,Maulina, W.,Isnaeni,Miftah, D.Y.N.,Sukmawati, N.,Rustami, E.,Azis, M.,Seminar, K.B.,Yuwono, A.S.,Cho, Y.H.,Alatas, H. Elsevier Sequoia 2014 Sensors and actuators. A Physical Vol.220 No.-

We have developed a novel ozone gas sensor based on one dimensional photonic crystal with two defects. In this platform, the gas is dissolved in a specific neutral buffer kalium iodide reagent to include the Beer Lambert effect. The corresponding photonic crystal which was fabricated by using sol-gel method consists of a high refractive index layer of TiO<SUB>2</SUB> and a low refractive index layer of SiO<SUB>2</SUB>. Prior to the fabrication of corresponding photonic crystal, we grew the TiO<SUB>2</SUB> and SiO<SUB>2</SUB> single layer separately in order to ensure that the performance of each layer fulfilled the required characteristics provided by our simulation. After that, the fabrication processed was conducted layer-by-layer and inspected by spectrophotometer. The performance test of the fabricated photonic crystal, including its validation, accuracy and sensitivity, was then conducted through spectroscopic treatment and we used ozonizer as the gas source. Validation test was performed by comparing the results with measurement using NBKI method and showed a good agreement. It was found that the accuracy value is up to 98.75%. Based on a statistical approach, we found that the limit of detection is 1.067μg/m<SUP>3</SUP> ambient air.

New Optimal design of D-STATCOM Compensation to Improve Power Quality Indices in Distribution Systems

Rahmat Allah Hooshmand,Amin Khodabakhshian,Mehdi Torabian Esfahani 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

In this paper the power quality phenomena regarding universal valid standards is first studied and analyzed. Then, in order to improve these phenomena in the distribution systems, the optimization design of compensating D-STATCOM by presenting a new method based on PSO (Particle Swarm Optimization) will be presented. This method not only improves the power quality indices and reduces distribution network harmonics, but also reduces active and reactive power oscillations of the system within reasonable limits. The voltage of the compensating DC capacitor is also satisfactorily stabilized within a reasonable limit.

Power Quality Enhancement in Power System with Electric Arc Furnaces by Shunt Active Power Filter Optimum Design

Rahmat Allah Hooshmand,Amin Khodabakhshian,Mehdi Torabian Esfahani 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

In this paper the design of optimum shunt active power filter in order to improve the power quality indices in power systems with electric arc furnaces will be discussed. The selected model for the arc is based on a combination of Cassie-Mayer equations. The conventional controllers are not capable of improving the power quality for these types of systems. Therefore, for improving the power quality indices a new method based on fuzzy controller is employed to design an optimum shunt active power filter. The simulation results show the advantages of using fuzzy control.

Higher order nonlocal nonlinear boundary value problems for fractional differential equations

Rahmat Ali Khan 대한수학회 2014 대한수학회보 Vol.51 No.2

In this paper, we study the method of upper and lower so- lutions and develop the generalized quasilinearization technique for the existence and approximation of solutions to some three-point nonlocal boundary value problems associated with higher order fractional differ- ential equations of the type cDq 0+u(t) + f(t, u(t)) = 0, t ∈(0, 1) u′(0) = u′(π), u′′(0) = 0, u′′′(0) = 0, . . . , u(n−1)(0) = 0, u(1) = u(π), where, n−1 < q < n, n(≥ 3) ∈ N, 0 < π,γ, <δ 1 and cDq 0+ is the Caputo fractional derivative of order q. The nonlinear function f is assumed to be continuous. In this paper, we study the method of upper and lower so- lutions and develop the generalized quasilinearization technique for the existence and approximation of solutions to some three-point nonlocal boundary value problems associated with higher order fractional differ- ential equations of the type cDq 0+u(t) + f(t, u(t)) = 0, t ∈ (0, 1) u′(0) = u′(π), u′′(0) = 0, u′′′(0) = 0, . . . , u(n−1)(0) = 0, u(1) = u(π), where, n−1 < q < n, n(≥3) ∈ N, 0 < π,γ, δ < 1 and cDq 0+ is the Caputo fractional derivative of order q. The nonlinear function f is assumed to be continuous.

Bio-inspired neuro-symbolic approach to diagnostics of structures

Rahmat A. Shoureshi,Tracy Schantz,Sun W. Lim 국제구조공학회 2011 Smart Structures and Systems, An International Jou Vol.7 No.3

Recent developments in Smart Structures with very large scale embedded sensors and actuators have introduced new challenges in terms of data processing and sensor fusion. These smart structures are dynamically classified as a large-scale system with thousands of sensors and actuators that form the musculoskeletal of the structure, analogous to human body. In order to develop structural health monitoring and diagnostics with data provided by thousands of sensors, new sensor informatics has to be developed. The focus of our on-going research is to develop techniques and algorithms that would utilize this musculoskeletal system effectively; thus creating the intelligence for such a large-scale autonomous structure. To achieve this level of intelligence, three major research tasks are being conducted: development of a Bio-Inspired data analysis and information extraction from thousands of sensors; development of an analytical technique for Optimal Sensory System using Structural Observability; and creation of a bio-inspired decision-making and control system. This paper is focused on the results of our effort on the first task, namely development of a Neuro-Morphic Engineering approach, using a neuro-symbolic data manipulation, inspired by the understanding of human information processing architecture, for sensor fusion and structural diagnostics.

Bio-inspired self powered nervous system for civil structures

Rahmat A. Shoureshi,Sun W. Lim 국제구조공학회 2009 Smart Structures and Systems, An International Jou Vol.5 No.2

Globally, civil infrastructures are deteriorating at an alarming rate caused by overuse, overloading, aging, damage or failure due to natural or man-made hazards. With such a vast network of deteriorating infrastructure, there is a growing interest in continuous monitoring technologies. In order to provide a true distributed sensor and control system for civil structures, we are developing a Structural Nervous System that mimics key attributes of a human nervous system. This nervous system is made up of building blocks that are designed based on mechanoreceptors as a fundamentally new approach for the development of a structural health monitoring and diagnostic system that utilizes the recently developed piezo-fibers capable of sensing and actuation. In particular, our research has been focused on producing a sensory nervous system for civil structures by using piezo-fibers as sensory receptors, nerve fibers, neuronal pools, and spinocervical tract to the nodal and central processing units. This paper presents up to date results of our research, including the design and analysis of the structural nervous system.

Improving the Dynamic Performance of Distribution Electronic Power Transformers Using Sliding Mode Control

Rahmat-Allah Hooshmand,Mohammad Ataei,Mohammad Hosein Rezaei 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

These days, the application of electronic power transformers (EPTs) is expanding in place of ordinary power transformers. These transformers can transmit power via three or four wire converters. Their dynamic performance is extremely important, due to their complex structure. In this paper, a new method is proposed for improving the dynamic performance of distribution electronic power transformers (DEPT) by using sliding mode control (SMC). Hence, to express the dynamic characteristics of a system, different factors such as the voltage unbalance, voltage sag, voltage harmonics and voltage flicker in the system primary side are considered. The four controlling aims of the improvement in dynamic performance include: 1) maintaining the input currents so that they are in sinusoidal form and in phase with the input voltages so they have a unity power factor, 2) keeping the dc-link voltage within the reference amount, 3) keeping the output voltages at a fixed amount and 4) keeping the output voltages in sinusoidal and symmetrical forms. Simulation results indicate the potential and capability of the proposed method in improving DEPT behavior.

Adventitious root culture for secondary metabolite production in medicinal plants: A Review

Rahmat, Endang,Kang, Youngmin The Korean Society of Plant Biotechnology 2019 식물생명공학회지 Vol.46 No.3

Medicinal plants are high-value natural resources that have been used as precautionary drugs by many people globally. The increasing global demand for bioactive compounds from medicinal plants has led to the overexploitation of many valuable species. One widely used approach to overcome this problem is the use of adventitious root cultures as a propagation strategy. This review examines the scientific research published globally on the application of adventitious root cultures for many medicinal plants. Adventitious roots generated under aseptic environments in suitable phytohormone-augmented medium exhibit high growth rates and production of important secondary metabolites. Parameters such as medium properties and composition, growth hormone type, and elicitation strategies for in vitro grown adventitious roots of medicinal plants, are the main topics discussed in this review. We also examine current developments in bioreactor system cultivation for plant bioactive compounds using adventitious root cultures, a technology with possible commercial applications, via several studies on adventitious root culture of medicinal plants in which bioreactor systems play a role. In conclusion, the development of adventitious root cultures for medicinal plants is highly useful because of their capability for vegetative propagation and germplasm preservation.