Additively manufactured nano-mechanical energy harvesting systems: advancements, potential applications, challenges and future perspectives

Ahmed Ammar,Azam Ali,Wang Yanen,Zhang Zutao,Li Ning,Jia Changyuan,Mushtaq Ray Tahir,Rehman Mudassar,Gueye Thierno,Shahid Muhammad Bilal,Basit Ali Wajid 나노기술연구협의회 2021 Nano Convergence Vol.8 No.37

Additively manufactured nano-MEH systems are widely used to harvest energy from renewable and sustainable energy sources such as wind, ocean, sunlight, raindrops, and ambient vibrations. A comprehensive study focusing on in-depth technology evolution, applications, problems, and future trends of specifically 3D printed nano-MEH systems with an energy point of view is rarely conducted. Therefore, this paper looks into the state-of-the-art technologies, energy harvesting sources/methods, performance, implementations, emerging applications, potential challenges, and future perspectives of additively manufactured nano-mechanical energy harvesting (3DP-NMEH) systems. The prevailing challenges concerning renewable energy harvesting capacities, optimal energy scavenging, power management, material functionalization, sustainable prototyping strategies, new materials, commercialization, and hybridization are discussed. A novel solution is proposed for renewable energy generation and medicinal purposes based on the sustainable utilization of recyclable municipal and medical waste generated during the COVID-19 pandemic. Finally, recommendations for future research are presented concerning the cutting-edge issues hurdling the optimal exploitation of renewable energy resources through NMEHs. China and the USA are the most significant leading forces in enhancing 3DP-NMEH technology, with more than 75% contributions collectively. The reported output energy capacities of additively manufactured nano-MEH systems were 0.5–32 mW, 0.0002–45.6 mW, and 0.3–4.67 mW for electromagnetic, piezoelectric, and triboelectric nanogenerators, respectively. The optimal strategies and techniques to enhance these energy capacities are compiled in this paper. Graphical Abstract

Peripheral Arterial Injuries in Pediatric Age Group

( Ahmed Ar. Ammar ) 대한외상학회 2016 大韓外傷學會誌 Vol.29 No.2

Purpose: Arterial injury in children is a challenging problem for its special characteristics. It is rare even during warfare. This review described a personal experience in the management and outcome of acute pediatric arterial injuries of extremities. Methods: Thirty-six children below age of 13 years were studied during period from 2004 through 2014 in Iraq. Results: Male patients were 27 (75%) and female were 9 (25%). Seven to twelve years old was the most affected age group. The incidence of iatrogenic injuries was greater in infants and toddlers while penetrating injuries were the most common in older children. Upper limbs arteries were affected in 17 (47.2%) and lower limb in 19 (52.8%) patients. Hard signs were the commonest mode of presentation (83.3%). Lateral wall tear and complete transection were the most frequent types of arterial injury (36.1% and 27.8% respectively). The most frequent procedures performed were end-to-end anastomosis and lateral arteriorrhaphy. Surgical outcome was good. In 27 cases distal pulsations were regained. Seven cases had impalpable distal pulses but still viable limbs. Limb length discrepancy was detected in one case. One case was complicated with limb loss. No death was recorded. Conclusion: Arterial injuries in children are age related. The proper treatment of arterial injuries in children requires high index of suspicion, early operative intervention and continuous postoperative follow-up throughout years of active growth. Angiogram has a limited role as a diagnostic tool in acute arterial injuries. [ J Trauma Inj 2016; 29: 37-42 ]

Improving the Detection of Malware Behaviour Using Simplified Data Dependent API Call Graph

Ammar Ahmed E. Elhadi,Mohd Aizaini Maarof,Bazara I. A. Barry 보안공학연구지원센터 2013 International Journal of Security and Its Applicat Vol.7 No.5

An Adaptive Scheduling Scheme for Cooperative Energy Harvesting Networks

Ahmed Ammar,Daryl Reynolds 한국통신학회 2015 Journal of communications and networks Vol.17 No.3

Energy harvesting devices have been proposed for sensor networking applications where batteries cannot be replaced, and cooperative communication schemes have been used to increase energy efficiency for wireless systems. Here, we develop transmission scheduling schemes formulti-terminal cooperative energy harvesting networks that maximize the packet delivery ratio, i.e., the probability that an event is reported successfully. We see that the proposed scheme provides virtually the same performance as the state-of-the-art threshold-based scheme, but does not require auxiliary parameter optimization. The proposed scheme also permits extensions to multiple cooperating nodes and sources, and it can be modified to accommodate fairness constraints.

Static stability and of symmetric and sigmoid functionally graded beam under variable axial load

Ammar Melaibari,Ahmed B. Khoshaim,Salwa A. Mohamed,Mohamed A. Eltaher 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.5

This manuscript presents impacts of gradation of material functions and axial load functions on critical buckling loads and mode shapes of functionally graded (FG) thin and thick beams by using higher order shear deformation theory, for the first time. Volume fractions of metal and ceramic materials are assumed to be distributed through a beam thickness by both sigmoid law and symmetric power functions. Ceramic–metal–ceramic (CMC) and metal–ceramic–metal (MCM) symmetric distributions are proposed relative to mid-plane of the beam structure. The axial compressive load is depicted by constant, linear, and parabolic continuous functions through the axial direction. The equilibrium governing equations are derived by using Hamilton’s principles. Numerical differential quadrature method (DQM) is developed to discretize the spatial domain and covert the governing variable coefficients differential equations and boundary conditions to system of algebraic equations. Algebraic equations are formed as a generalized matrix eigenvalue problem, that will be solved to get eigenvalues (buckling loads) and eigenvectors (mode shapes). The proposed model is verified with respectable published work. Numerical results depict influences of gradation function, gradation parameter, axial load function, slenderness ratio and boundary conditions on critical buckling loads and mode-shapes of FG beam structure. It is found that gradation types have different effects on the critical buckling. The proposed model can be effective in analysis and design of structure beam element subject to distributed axial compressive load, such as, spacecraft, nuclear structure, and naval structure.

Effectiveness of laser-engineered copper-nickel titanium versus superelastic nickel-titanium aligning archwires: A randomized clinical trial

Ahmed Omar Khairullah,Kadhum Ammar Salim 대한치과교정학회 2024 대한치과교정학회지 Vol.54 No.1

Objective: To compare the effectiveness of laser-engineered copper-nickel titanium (SmartArch) and superelastic nickel-titanium (SENT) archwires in aligning teeth and inducing root resorption and pain experienced by patients. Methods: Two-arm parallel groups with a 1:1 allocation ratio were used. The participants were patients aged 11.5 years and older with 5–9 mm of mandibular anterior crowding who were indicated for non-extraction treatment. The primary outcome was alignment effectiveness, assessed using Little’s irregularity index (LII) over 16 weeks with a single wire (0.016-inch) in the SmartArch group and 2 wires (0.014- and 0.018-inch) in the SENT group (8 weeks each). Secondary outcomes included root resorption evaluated by pre- and post-intervention periapical radiographs and pain levels recorded by the participants during the first week. Results: A total of 40 participants were randomly allocated into 2 groups; 33 completed the study and were analyzed (16 in the SmartArch group and 17 in the SENT group, aged 16.97 ± 4.05 years). The total LII decrease for the SmartArch and SENT groups was 5.63 mm and 5.29 mm, respectively, which was neither statistically nor clinically significant. Root resorption was not significantly different between the groups. The difference in pain levels was not statistically significant for the first 5 days following wire placement; however, there was a significant difference favoring the SENT group in the final 2 days. Conclusions: SmartArch and SENT archwires were similarly effective during the alignment phase of orthodontic treatment. Root resorption should be observed throughout the treatment with either wire. SmartArch wires demonstrated higher pain perception than SENT wires.

Dynamic characteristics of multi-phase crystalline porous shells with using strain gradient elasticity

Ahmed, Ridha A.,Al-Maliki, Ammar F.H.,Faleh, Nadhim M. Techno-Press 2020 Advances in nano research Vol.8 No.2

This paper studies forced vibrational behavior of porous nanocrystalline silicon nanoshells under radial dynamic loads using strain gradient theory (SGT). This type of material contains many pores inside it and also there are nano-size grains which define the material character. The formulation for nanocrystalline nanoshell is provided by first order shell theory and a numerical approach is used in order to solve nanoshell equations. SGT gives a scale factor related to stiffness hardening provided by nano-grains. For more accurate description of size effects due to nano-grains or nano-pore, their surface energy influences have been introduced. Surface energy of inclusion exhibit extraordinary influence on dynamic response of the nanoshell. Also, dynamic response of the nanoshell is affected by the scale of nano-grain and nano-pore.

Effect of recycled polypropylene fiber on high strength concrete and normal strength concrete properties

Touahri, Ahmed,Branci, Taieb,Yahia, Ammar,Ezziane, Karim Techno-Press 2021 Advances in materials research Vol.10 No.4

An experimental study was undertaken to evaluate the performance of recycled polypropylene fiber (RPF) in concrete. The RPF materials were recycled from woven bags and used in concrete at various volume fractions corresponding to 0.1%, 0.2%, and 0.3%. Two different classes of strength, corresponding to normal and high strength concrete, were investigated. Fiber was used as substitution of coarse aggregate in concrete. The dosage of fiber was used at relatively lower dosages to avoid altering fluidity and to limit the reduction in coarse aggregate content. On the other hand, a commercial polypropylene fiber (PPF) was used at equivalent dosages than RPF for comparisons purposes. Test results indicated that optimized RPF volumes can secure comparable mechanical performance than those obtained with commercial PPF. On the other hand, the use of both fiber types resulted in lower compressive strength (10 to 20%), higher flexural strength (up to 27%), and lower elastic modulus (by 16%). Furthermore, the use of RPF type reduced the drying shrinkage (6 to 10%) of normal and high strength concrete types and increased the permeable pore void of both concrete types.

Effects of pH and Chloride Concentration on Corrosion Behavior of Duplex Stainless Steel and Titanium Alloys Ti 6Al 2Nb 1Ta 1Mo at Elevated Temperature for Pump Impeller Applications

Aymen A. Ahmed,Ammar Yaseen Burjes,Marwan Zuhair Elias 한국부식방식학회 2022 Corrosion Science and Technology Vol.21 No.6

The objective of this study was to determine effects of temperatures and pH of sodium chloride solution with MgCl2 ions on corrosion resistance of duplex stainless-steel X2CrNiMoN22-5-3 (DSS) and Ti 6Al 2Nb1Ta1Mo (Ti). Effects of sodium chloride concentration on corrosion resistance were also studied. Corrosion behavior and pitting morphology of duplex stainless steel (DSS) and Ti alloys were evaluated through potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). It was found that a decrease in pH significantly reduced the corrosion resistance of both alloys. Changes in chloride concentration and temperature had more substantial impact on corrosion behavior of DSS than on Ti alloys. Pitting corrosion was formed on DSS samples under all conditions, whereas crevice corrosion was developed on Ti samples with the presence of magnesium chloride at 90 oC. In conclusion, magnesium chloride ions in an exceedingly strong acidity solution appear to interact with re-passivation process at the surface of these alloys and influence the resulting surface topography.

Polynomial Dynamic Output-feedback Controllers for Positive Polynomial Fuzzy Systems with Time Delay

Imen Iben Ammar,Hamdi Gassara,Mohamed Chaabane,Ahmed El Hajjaji 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.8

This paper investigates the stability and stabilization problems of positive polynomial fuzzy uncertain interval models with time delay. Using the polynomial output feedback fuzzy control strategy, the design problem is firstly studied by considering the unmeasured states and measurable premise variables. Then, the control design problem is extended for both the unmeasurable states and unmeasurable premise variables. To study the considered analysis and design problems, a line-integral polynomial fuzzy Lyapunov function with polynomial terms depending of the estimated states is proposed. For each case, the proposed design conditions of the polynomial dynamic output feedback fuzzy controllers guarantying both the stability and the positivity of the resulting closed loop systems, are solved using the Sum of Squares (SOS) approach with tacking into account the positivity of the error signals. Finally, simulation examples are given to show the effectiveness of the proposed approaches.