A numerical investigation on the heat and fluid flow of various nanofluids on a stretching sheet

Following the necessity of investigating fluid flow and heat transfer in the stretching sheet problem and effect of nanofluids on them, performance of various nanofluids were investigated in the present study. Three base fluids (deionized water, ethylene glycol, and engine oil) in combination with 18 nanoparticles (metals and their oxides) were investigated. While experimental methods are preferable, a mathematical model was developed and solved by applying differential quadrature method due to lack of such experimental data. With the results obtained in the real dimensions, the error caused by the cancellation of the viscosity effect due to the dimensionless variables was omitted. Effects of magnetic field and volume fraction of nanoparticle on the fluid flow and heat transfer characteristics were investigated. Highest heat transfer rate as well as small amounts of shear stress was obtained for deionized water–Al and deionized water–Mg nanofluids. Increasing volume fraction of nanoparticle was observed to increase both heat transfer and shear stress rates, while presence of a magnetic field caused an increase in shear stress and decrease in heat transfer rate.     

Node Throughput Analysis of Decentralized Wireless Networks Using Multibeam Antennas in Multipath Environments

The use of multibeam antennas (MBAs) in decentralized wireless networks significantly increases the throughput by improving spatial reuse and extending coverage compared with single-beam antennas. The throughput performance may, however, degrade in multipath environments due to the fact that multipath propagation increases the probability of collision among different users. Based on the probability of collision, accurate analytical expressions are derived for the node throughput gain (NTG) of a wireless network using MBAs in quasi-stationary multipath environments. The results show that a higher number of propagation paths cause more frequent collisions and thus yield lower node throughput.

Design and Implementation to Authentication over a GSM System Using Certificate-Less Public Key Cryptography (CL-PKC)

Recent years, the mobile technology has experienced a great increment in the number of its users. The GSM’s architecture provides different security features like authentication, data/signaling confidentiality and secrecy of user yet the channel is susceptible to replay and interleaved. It always remains relevant as it is important in all types of application. Global system for mobile (GSM) communications has become the most popular standard for digital cellular communication. The GSM security system depends on encryption, authentication algorithms and information from SIM card. In this research paper, we proposed the design and implementation of a new authentication scheme by using certificate-less public key cryptography (CL-PKC) over the GSM system was attempted to miss some system detail. This research paper, we also proposed the GSM system and its security and public key cryptography with a focus in the CL-PKC; the CL-PKC is a simple, useful and robust security scheme designed and implemented over GSM. Our approach is more efficient than other competing topologies. We solved the GSM problem in A3 algorithm such as eavesdropping and this problem solved by CL-PKC because of its robustness against this type of attack by providing mutual authentication make the system more secure.     

Comparative study on the role of gelatin,chitosan and their combination as tissue engineered scaffolds on healing and regeneration of critical sized bone defects: an in vivo study

Gelatin and chitosan are natural polymers that have extensively been used in tissue engineering applications. The present study aimed to evaluate the effectiveness of chitosan and gelatin or combination of the two biopolymers (chitosan–gelatin) as bone scaffold on bone regeneration process in an experimentally induced critical sized radial bone defect model in rats. Fifty radial bone defects were bilaterally created in 25 Wistar rats. The defects were randomly filled with chitosan, gelatin and chitosan–gelatin and autograft or left empty without any treatment (n?=?10 in each group). The animals were examined by radiology and clinical evaluation before euthanasia. After 8?weeks, the rats were euthanized and their harvested healing bone samples were evaluated by radiology, CT-scan, biomechanical testing, gross pathology, histopathology, histomorphometry and scanning electron microscopy. Gelatin was biocompatible and biodegradable in vivo and showed superior biodegradation and biocompatibility when compared with chitosan and chitosan–gelatin scaffolds. Implantation of both the gelatin and chitosan–gelatin scaffolds in bone defects significantly increased new bone formation and mechanical properties compared with the untreated defects (P?<?0.05). Combination of the gelatin and chitosan considerably increased structural and functional properties of the healing bones when compared to chitosan scaffold (P?<?0.05). However, no significant differences were observed between the gelatin and gelatin–chitosan groups in these regards (P?>?0.05). In conclusion, application of the gelatin alone or its combination with chitosan had beneficial effects on bone regeneration and could be considered as good options for bone tissue engineering strategies. However, chitosan alone was not able to promote considerable new bone formation in the experimentally induced critical-size radial bone defects.     

GENERALIZED KINEMATIC VISCOSITY-TEMPERATURECORRELATION FOR UNDEFINED PETROLEUM FRACTIONS OF IBP – 95°C TO 455°C+ BOILING RANGES

ABSTRACT

A generalized kinematic viscosity-temperature correlation for undefined petroleum fractions of all boiling ranges including 455^+°C fractions have been developed to represent the data for a wide range of temperature from 30 to 200°C. The correlation is based on experimental kinematic viscosity data for twenty TBP fractions of Arab heavy, Arab medium, Arab light and Arab extra-light crude oils. The proposed correlation has been found to fit all the eperimental data consisting of 248 measurements of the kinematic viscosity with an overall average absolute deviation of 9.07% compared to 15.47% given by ASTM method.     

Materials selection for thermal comfort in passive solar buildings

This paper presents the results of a combined analytical, computational, and experimental study of the key parameters for selecting affordable materials and designing for thermal comfort in passive solar buildings. The heat transfer across the walls of buildings is modeled using a simple heat diffusion model. In this way, the passive heat storage from the sun (passive solar) and the heat load from internal heat sources are stored in the walls of buildings that provide internal cooling during the day and internal heating at night. The simple analytical model of heat diffusion is used to identify the merit indices for the optimization of affordable passive solar performance. The time dependence of wall/internal temperature is then simulated using a simple finite difference model. The results from the analytical model and finite difference model are validated by conducting temperature measurements in two affordable housing complexes in Egypt. The implications of the results are then discussed for the design of thermal comfort in affordable housing.     

Cognitive IoT-Cloud Integration for Smart Healthcare: Case Study for Epileptic Seizure Detection and Monitoring

We propose a cognitive Internet of Things (IoT)–cloud-based smart healthcare framework, which communicates with smart devices, sensors, and other stakeholders in the healthcare environment; makes an intelligent decision based on a patient’s state; and provides timely, low-cost, and accessible healthcare services. As a case study, an EEG seizure detection method using deep learning is also proposed to access the feasibility of the cognitive IoT–cloud smart healthcare framework. In the proposed method, we use smart EEG sensors (apart from general healthcare smart sensors) to record and transmit EEG signals from epileptic patients. Thereafter, the cognitive framework makes a real-time decision on future activities and whether to send the data to the deep learning module. The proposed system uses the patient’s movements, gestures, and facial expressions to determine the patient’s state. Signal processing and seizure detection take place in the cloud, while signals are classified as seizure or non-seizure with a probability score. The results are transmitted to medical practitioners or other stakeholders who can monitor the patients and, in critical cases, make the appropriate decisions to help the patient. Experimental results show that the proposed model achieves an accuracy and sensitivity of 99.2 and 93.5%, respectively.     

An anonymous and provably secure authentication scheme for mobile user

Chebyshev chaotic map is an important tool used in the domain of cryptography to develop different schemes for numerous applications. In 2014, Lin put forwarded a mobile user authentication system using dynamic identity and chaotic map. Lin declared that the scheme offers mutual authentication and session key agreement between user and server. Moreover, they stated that the scheme offers user anonymity and resilience against known attacks. However, we carefully examined Lin's scheme and found that it is no longer usable for practical applications as (i) it has no facility to identify the wrong password and identity, which are inputted by the user during login and password update phases, (ii) it has no facility to protect user impersonation attack, and (iii) it has the problem of session key forward secrecy. We put forwarded an enhanced scheme based on extended chaotic map to repair the fragilities of Lin's scheme. We formally examined the security of our scheme and demonstrated that it is provably secured in random oracle model. Further, we presented some informal cryptanalysis to make sure that the enhanced scheme is secure from known attacks. Our scheme is also computation efficient against other competitive protocols. Copyright © 2016 John Wiley & Sons, Ltd.     

In situ small-scale hydrogen embrittlement testing made easy: An electrolyte for preserving surface integrity at nano-scale during hydrogen charging

An electrolyte for electrochemical hydrogen charging of corrosion-susceptible alloys is developed, which preserves the surface integrity at nano-scale by minimizing the surface roughness alternation. To assure the formation and adsorption of the hydrogen from the electrolyte, permeation tests were performed on Fe 3 wt%Si ferritic steel. X-ray photoelectron spectroscopy method was used to check the effect of the glycerol-based solution on the chemical composition of the sample surface. The surface analysis revealed minimal chemical and topography alteration on the surface after different electrochemical treatments. Various types of in situ small-scale mechanical tests such as nano-indentation, micro-pillar compression, and micro-cantilever bending tests were performed inside this electrolyte while the samples being charged with hydrogen under cathodic potential. These small-scale mechanical tests showed that the solution facilitates studying hydrogen embrittlement in nano- or micro-scale.