Tarig Mohamed Ahmed^*

CMC-Computers, Materials & Continua, Vol.72, No.2, pp. 3849-3862, 2022, DOI:10.32604/cmc.2022.025582 - 29 March 2022

Abstract Mobile Agent has many benefits over traditional distributed systems such as reducing latency, bandwidth, and costs. Mobile Agent Systems are not fully utilized due to security problems. This paper focuses on mobile agent protection against malicious hosts. A new security mechanism called Checkpoints has been proposed. Checkpoint Mechanism (CPM) aims to protect Mobile Agent against malicious hosts in case of Capturing and Integrity attacks. CPM assumes using a free-roaming mobility mechanism by Mobile agent systems. The main idea behind CPM is to generate multiple versions of Mobile Agent. The multiple version is used to recover… More >

Bing Zhang¹, Sujie Yang¹, Mengru Liu¹, Panyue Wen², Xiuyu Liu¹, Gang Tang^1,*, Xiangrong Xu^3,4,*

Journal of Renewable Materials, Vol.10, No.5, pp. 1201-1220, 2022, DOI:10.32604/jrm.2022.018047 - 22 December 2021

Abstract Biomass phytic acid has potential flame retardant value as the main form of phosphorus in plant seeds. In this study, phytate-based flame retardants aluminum phytate (PA-Al) and iron phytate (PA-Fe) were synthesized and characterized. Subsequently, they were introduced into rigid polyurethane foam (RPUF) as flame retardants by one-step water-blown method. The results indicated that RPUF/PA-Fe30 exhibited the highest char residue of 22.1 wt%, significantly higher than 12.4 wt% of RPUF. Cone calorimetry analysis showed that the total heat release (THR) of RPUF/PA-Al30 decreased by 17.0% and total smoke release (TSR) decreased by 22.0% compared with pure RPUF, More > Graphic Abstract

Xiaojing Hou, Yongyou Cao^*, Wenfeng Mao, Zheng Wang, Jiwu Yuan

FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.5, pp. 859-869, 2021, DOI:10.32604/fdmp.2021.015967 - 05 July 2021

Abstract Two models are defined for predicting the trajectory of a foam jet originating from a fire monitor (hydrant) and the related intensity drop point. An experimental framework is also defined and used accordingly to compare real-time data with the predictions of such models. This mixed theoretical-experimental approach is proven to be effective for the determination of otherwise unknown coefficients which take into account several important factors such as the operation pressure, the elevation angle and the nozzle diameter. It is shown that the mean absolute error is smaller than 20%. More >

Jialiang Zhang¹, Shumei He¹, Tongjing Liu^2,*, Tianlu Ni¹, Jian Zhou^2,3, Fang Huang¹

FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.5, pp. 931-946, 2021, DOI:10.32604/fdmp.2021.015638 - 05 July 2021

Abstract During the displacement of water plugging with binary flooding in internally heterogeneous reservoirs, it is essential to understand the distributions of remaining oil as well as the oil displacement mechanisms at different stages. In this study, two types of internally heterogeneous systems, i.e., vertical and horizontal wells are investigated experimentally through a microscopic approach. The results show that plugging agent types have a greater impact on oil recovery than well types, and foam injection can enhance oil recovery more effectively than gel injection. Additionally, the injection sequence of plugging agents significantly affects oil displacement efficiency. More >

Xiaohua Gu^1,*, Shiwei Lyu¹, Siwen Liu²

Journal of Renewable Materials, Vol.9, No.11, pp. 1913-1926, 2021, DOI:10.32604/jrm.2021.015400 - 04 June 2021

Abstract A bi-component alcoholysis agent containing propylene glycol (PG) and ethanolamine (ETA) was used to catalyst the degradation of the waste polyurethane rigid foam. The oligomer polyols obtained through degradation were used as raw materials to produce recycled polyurethane rigid foam composites with lignin as reinforcing filler. The effect of alcoholysis mass ratio on degradation was investigated by analyzing the viscosity, hydroxyl content and chemical structure of the degradation products. The effect of lignin addition on the properties of regenerated polyurethane rigid foam were investigated by analyzing water absorption rate, compressive strength, porosity, thermal stability, thermal More >

Christian Brütting¹, Julia Dreier², Christian Bonten², Volker Altstädt¹, Holger Ruckdäschel^1,*

Journal of Renewable Materials, Vol.9, No.11, pp. 1859-1868, 2021, DOI:10.32604/jrm.2021.016244 - 04 June 2021

Abstract Polylactide (PLA) bead foams show a high potential regarding their applicability in packaging or consumer products. Concerning the comparable properties of PLA to Polystyrene (PS) and the good CO₂ footprint it represents a potential alternative to petroleum-based polymer foams. However, foaming of PLA is challenging, due to its low melt strength, therefore chemical modifiers are often used. Concerning the bead foam technology regarding PLA, the available literature is limited so far. Within this study, the bead foaming behavior of neat and modified amorphous PLA was investigated. The material was modified by talc and an epoxy-based chain More >

Mohammad Javad Jafari¹, Mohsen Niknam Sharak², Ali Khavanin³, Touraj Ebadzadeh⁴, Mahmood Fazlali⁵, Rohollah Fallah Madvari^6,*

Sound & Vibration, Vol.55, No.2, pp. 117-130, 2021, DOI:10.32604/sv.2021.09729 - 21 April 2021

Abstract Fabricating of metal foams with desired morphological parameters including pore size, porosity and pore opening is possible now using sintering technology. Thus, if it is possible to determine the morphology of metal foam to absorb sound at a given frequency, and then fabricate it through sintering, it is expected to have optimized metal foams for the best sound absorption. Theoretical sound absorption models such as Lu model describe the relationship between morphological parameters and the sound absorption coefficient. In this study, the Lu model was used to optimize the morphological parameters of Aluminum metal foam… More >

Xiaohua Gu, Hongxiang Luo^*, Shiwei Lv, Peng Chen

Journal of Renewable Materials, Vol.9, No.7, pp. 1253-1266, 2021, DOI:10.32604/jrm.2021.014876 - 18 March 2021

Abstract Dramatically increasing waste polyurethane rigid foam (WPRF) draws the attention of the world. A mixture of ethylene glycol (EG) and diethylene glycol (DEG) is used as glycolysis agents. WPRF was subjected to alcoholysis using different catalysts which are titanium ethylene glycol and potassium hydroxide to obtain recycled polyol, respectively. The effect of a different catalyst on the viscosity and hydroxyl value of recycled polyol is discussed. The regenerated polyurethane (RPU) is performed using the recycled polyol. Infrared spectrum, compressive strength, apparent density, water absorption, scanning electron microscope, and thermogravimetric analysis are carried out to investigate… More >

Yun Zhao, Shi Yan^*, Jiale Jia

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.3, pp. 1251-1274, 2021, DOI:10.32604/cmes.2021.013478 - 19 February 2021

Abstract In this study, the pyramidal lattice stitched foam sandwich composite materials were manufactured by integrating top and bottom panels with pyramidal lattice core to overcome the weak interface between the core and the skins of the sandwich structure. The influence of the reinforcing core rods on the mechanical properties including compressive, shear, and three-point bending performances of the foam sandwich composite materials were revealed through theoretical analysis and comparative experiments. The theoretical predictions were consistent with the experimental results. Compressive test, shear test and three-point bending test were performed. The experimental results show that the… More >

Yang Liu¹, Jianjun Xie^1,*, Peng Hao¹, Ying Shi¹, Yonggen Xu^2,3, Xiaoqing Ding^2,3

Journal of Renewable Materials, Vol.9, No.2, pp. 237-253, 2021, DOI:10.32604/jrm.2021.012228 - 15 December 2020

Abstract Foam glass is a new green material to make use of waste glass and is popular for its energy-saving and light weight features. The problems in the current study of foam glass is that its properties require improvement to match the growing demands of application specific standards. Properties of foam glass is related to its porous structure, which is affected by various factors. The influence of raw material component, foaming agents and sintering system on the porous structure and properties of foamed glass is studied. Density decreases with the decrease of quartz and barite content.… More >