Electro-actuation characteristics of Cl₂ and SF₆ plasma-treated IPMC actuators

Saher, Saim,Kim, Woojin,Moon, Sungwon,Jin Kim, H,Kim, Yong Hyup Institute of Physics Publishing 2010 Smart materials & structures Vol.19 No.10

<P>This paper describes plasma treatments that improve the actuation properties by modifying the surface morphology of ionic polymer metal composites (IPMC). The proposed Cl<SUB>2</SUB> and SF<SUB>6</SUB> plasmas change the surface appearance of the electroactive polymer, and scanning electron microscopy (SEM) of the plasma-treated surfaces reveals the development of round and cone-shaped microstructures. After electroless chemical metal plating, these microstructures significantly alter the characteristics of the IPMC electrode. In plasma-treated IPMCs, the densely packed platinum nanoparticles have produced a relatively thick electrode layer. This configuration has led to the improvement in the electrical properties of the IPMC: surface resistance is noticeably decreased, whereas electrical capacitance is increased. These changes in the electrical properties have considerably enhanced the actuation parameters: displacement, force and operational life are increased by more than three times relative to the conventional IPMC. Our experimental data suggest a relationship between the IPMC actuator’s electrical properties and actuation parameters: actuators with lower surface resistance generate large deflection and actuators with higher capacitance generate large actuation force. The actuation tests including coin lifting suggests the potential of the modified IPMC for artificial muscle applications.</P>

Generalized Optimal and Explicit PI/PID Tuning Formulas for Underdamped Second-order Systems

Saher Albatran,Issam A. Smadi,Hussein A. Bataineh 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.4

This study aims to propose generalized formulas in an explicit form to optimally tune the gains of the proportional-integral (PI) and proportional-integral-derivative (PID) controllers of an underdamped second-order system. Unlike other methods used in literature, the controller gains are tuned explicitly based on the known system parameters of the second-order system, namely: the damping ratio and the natural frequency. The proposed accurate and one-step formulas do not need any further effort to effectively control any given second-order system while keeping the desired performance indices within near-optimal specifications. The proposed work relies on a restricted deadbeat response criterion and cascaded surface curve fitting procedure to end by near-optimal controller gains tuning formulas. A particle swarm optimization (PSO) method is employed to optimize the primary tuned gains for wide-range of system frequency. The proposed formulas are tested and simulated to demonstrate their effectiveness with comparisons with the closest common related gains tuning methods. Based on the comprehensive analysis, the proposed work ensures 2% maximum percentage overshoot when the proposed formulas are adopted to tune the gains of the PID controllers. Different comparisons are carried out to show the effectiveness of theproposed work.

Robust H∞ Filtering for Uncertain Discrete-time Descriptor Systems

Sahere Beidaghi,Ali Akbar Jalali,Ali Khaki-Sedigh,Bijan Moaveni 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.3

This paper considers the robust H∞ filtering problem for uncertain discrete-time descriptor systems. Aclass of uncertain systems with norm-bounded uncertainties is considered. The necessary and sufficient conditionfor solvability of the robust full-order H∞ filtering is introduced which is generally less conservative than thoseexisting sufficient conditions only. Explicit expressions of these filters are given. In addition to the full-orderfiltering problem, the robust reduced-order H∞ filtering is also addressed by using slack variables technique in newsufficient conditions. The parameters of reduced-order filters are directly extracted from the solvability conditions. All the above conditions are convex and are expressed in term of linear matrix inequalities (LMIs) by using theoriginal system matrices. The results generalize the previously developed H∞ filter design for standard discretetimesystems. A numerical example is presented to demonstrate the effectiveness of the proposed approaches.

Use of Blockchain to Support the Security of Internet of Things: A Review

Saher Un Nisa,Maryam Khalid International Journal of Computer ScienceNetwork S 2023 International journal of computer science and netw Vol.23 No.7

Internet of Things (IoT) is now spreading everywhere. It's the technology of every person's need so we can't step back from IoT but we can secure it as it is spreading quickly so it has greater chances of danger and being misused. There is an urgent need to make IoT devices secure from getting cracked or hacked. A lot of methods had tried and still trying to mitigate IoT security issues. In this paper Blockchain is going to be the solution of most of the IoT issues or problems. We have discussed or highlighted security issues with centralized IoT and then provided solution of such security challenges through the use of blockchain because is based on a decentralized technology that is hard to modify or update.

Photocatalytic conversion of acetate into molecular hydrogen and hydrocarbons over Pt/TiO₂: pH dependent formation of Kolbe and Hofer-Moest products

Hamid, Saher,Ivanova, Irina,Jeon, Tae Hwa,Dillert, Ralf,Choi, Wonyong,Bahnemann, Detlef W. Elsevier 2017 Journal of catalysis Vol.349 No.-

<P><B>Abstract</B></P> <P>The photocatalytic generation of H<SUB>2</SUB> and hydrocarbons from aqueous acetic acid has been studied employing TiO<SUB>2</SUB> P25-based photocatalyst particles. The effect of pH on the distribution of reaction products and their formation rates during the photochemical as well as the photoelectrochemical oxidation of acetic acid has been investigated. The photocatalytic formation rates for H<SUB>2</SUB> and hydrocarbons were found to be higher for Pt-loaded TiO<SUB>2</SUB> than for bare TiO<SUB>2</SUB>. The major reaction products resulting from the photocatalytic decomposition of aqueous acetic acid, as determined quantitatively in the gas phase, were found to be H<SUB>2</SUB>, CO<SUB>2</SUB>, and CH<SUB>4</SUB>. Furthermore, traces of C<SUB>2</SUB>H<SUB>6</SUB>, C<SUB>3</SUB>H<SUB>8</SUB>, CO, CH<SUB>3</SUB>CHO, HCHO, CH<SUB>3</SUB>OH, C<SUB>2</SUB>H<SUB>5</SUB>OH, and HCOOH were also detected. After 15h of illumination, the average formation rates of H<SUB>2</SUB>, CO<SUB>2</SUB>, CH<SUB>4</SUB>, and C<SUB>2</SUB>H<SUB>6</SUB> evolved at pH 2 were found to be 22, 65, 35, and 2µmol/h, respectively. The ratio of H<SUB>2</SUB> to hydrocarbons strongly depends on the pH values, <I>i.e.,</I> at acidic pH the ratio of H<SUB>2</SUB> to CH<SUB>4</SUB> formation was found to be 0.6. On the contrary, at neutral and basic pH values negligible amounts of hydrocarbons were formed and H<SUB>2</SUB> was found to be the main product with formation rates of 12 and 5µmol/h at pH 7 and 11, respectively. It is therefore assumed that the hydroxide ion has a significant effect on the reaction pathways. Due to the fact that methanol and ethanol are formed as reaction products, water or hydroxide ions are apparently required for the formation of the major oxidizing agent, that is the hydroxyl radical. Herein, a detailed mechanism for the photocatalytic decomposition of acetic acid at different pH values is presented.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Photocatalytic decomposition of acetic acid results in formation of H<SUB>2</SUB>, CH<SUB>4</SUB>, and C<SUB>2</SUB>H<SUB>6</SUB>. </LI> <LI> pH greatly influences product distribution and formation rates. </LI> <LI> Photocatalytic transformation of acetate proceeds by Kolbe reaction at pH<7. </LI> <LI> Photocatalytic transformation of acetate proceeds by Hofer-Moest reaction at pH≥7. </LI> <LI> A significant formation rate for H<SUB>2</SUB> was found for 2≤pH≤9. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Breast Cancer in Pakistan - a Critical Appraisal of the Situation Regarding Female Health and Where the Nation Stands?

Basra, Muhammad Asim R,Saher, Manzoor,Athar, Muhammad Makshoof,Raza, Muhammad Hashim Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.7

Breast cancer (BC) is the most common malignancy of women worldwide. In the past it was considered as disease of older middle aged women, but the incidence of BC in young females is growing in recent years concordant with studies in Pakistan. In this paper, we reviewed the mutant functions of tumor suppressor genes (BRCA1, BRCA2, p53, ATM and PTEN), epigenetic transformation and involvement of estrogen receptors in development of breast cancer. We further reviewed the current situation of BC in Pakistan that depicts a higher incidence in young females. According to SKMCH and RC data, age group 45-49 years is more prone to BC with high rate of incidence 45.42%. A few studies explored the high expression of ER, PR and HER-2/neu in Pakistani females. Moreover, presence of BRCA1 (c.1961dupA) mutation in Pakistani shows concordance with data in different areas of world. But we are unable to find an authentic study that can explore epigenetic based transformation of breast tumors in Pakistan. This area of research needs more attention to explore the complete picture of BC in Pakistan.

Modeling of RC shear walls strengthened by FRP composites

Mohammed A. Sakr,Saher R. El-khoriby,Tarek M. Khalifa,Mohammed T. Nagib 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.3

RC shear walls are considered one of the main lateral resisting members in buildings. In recent years, FRP has been widely utilized in order to strengthen and retrofit concrete structures. A number of experimental studies used CFRP sheets as an external bracing system for retrofitting of RC shear walls. It has been found that the common mode of failure is the debonding of the CFRP-concrete adhesive material. In this study, behavior of RC shear wall was investigated with three different micro models. The analysis included 2D model using plane stress element, 3D model using shell element and 3D model using solid element. To allow for the debonding mode of failure, the adhesive layer was modeled using cohesive surface-to-surface interaction model at 3D analysis model and node-to-node interaction method using Cartesian elastic-plastic connector element at 2D analysis model. The FE model results are validated comparing the experimental results in the literature. It is shown that the proposed FE model can predict the modes of failure due to debonding of CFRP and behavior of CFRP strengthened RC shear wall reasonably well. Additionally, using 2D plane stress model, many parameters on the behavior of the cohesive surfaces are investigated such as fracture energy, interfacial shear stress, partial bonding, proposed CFRP anchor location and using different bracing of CFRP strips. Using two anchors near end of each diagonal CFRP strips delay the end debonding and increase the ductility for RC shear walls.

Message Security Level Integration with IoTES: A Design Dependent Encryption Selection Model for IoT Devices

Saleh, Matasem,Jhanjhi, NZ,Abdullah, Azween,Saher, Raazia International Journal of Computer ScienceNetwork S 2022 International journal of computer science and netw Vol.22 No.8

The Internet of Things (IoT) is a technology that offers lucrative services in various industries to facilitate human communities. Important information on people and their surroundings has been gathered to ensure the availability of these services. This data is vulnerable to cybersecurity since it is sent over the internet and kept in third-party databases. Implementation of data encryption is an integral approach for IoT device designers to protect IoT data. For a variety of reasons, IoT device designers have been unable to discover appropriate encryption to use. The static support provided by research and concerned organizations to assist designers in picking appropriate encryption costs a significant amount of time and effort. IoTES is a web app that uses machine language to address a lack of support from researchers and organizations, as ML has been shown to improve data-driven human decision-making. IoTES still has some weaknesses, which are highlighted in this research. To improve the support, these shortcomings must be addressed. This study proposes the "IoTES with Security" model by adding support for the security level provided by the encryption algorithm to the traditional IoTES model. We evaluated our technique for encryption algorithms with available security levels and compared the accuracy of our model with traditional IoTES. Our model improves IoTES by helping users make security-oriented decisions while choosing the appropriate algorithm for their IoT data.

Cyclic behaviour of infilled steel frames with different beam-to-column connection types

Mohammed A. Sakr,Mohammed M. Eladly,Tarek Khalifa,Saher El-Khoriby 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.5

Although numerous researchers demonstrated the significant difference in performance between the various beam-to-column connection types, most of the previous studies in the area of infilled steel frames focused on the behaviour of frames with welded connections. Therefore, there is a need for conducting studies on infilled steel frames with other common connection types (extended endplate with and without rib stiffeners, flush endplate and shear connections). In this paper, firstly, a two-dimensional finite-element model simulating the cyclic response of infilled steel frames was presented. The infill-frame interaction, as well as the interactions between connections’ components, were properly modelled. Using the previously-validated model, a parametric study on infilled steel frames with five different beam-to-column connection types, under cyclic loading, was carried out. Several parameters, including infill material, fracture energy of masonry and infill thickness, were investigated. The results showed that the infilled frames with welded connections had the highest initial stiffness and load-carrying capacity. However, the infilled frames with extended endplate connections (without rib stiffeners) showed the greatest energy dissipation capacity and about 96% of the load-carrying capacity of frames with welded connections which indicates that this type of connection could have the best performance among the studied connection types. Finally, a simplified analytical model for estimating the stiffness and strength of infilled steel frames (with different beam-to-column connection types) subjected to lateral cyclic loading, was suggested.