Alireza Haghighat Nezhad - Academia.edu (original) (raw)

Papers by Alireza Haghighat Nezhad

Anonymity and location privacy are two important aspects of network security for users. This thes... more Anonymity and location privacy are two important aspects of network security for users. This thesis is concerned with location privacy and anonymity in multihop wireless ad hoc networks. More specifically, it proposes techniques to protect these features from being violated as a by-product of ad hoc routing protocols. We have proposed a novel destination-centric routing approach called Destination Controlled Routing (DCR) in which the destination is the master and controls how packets are delivered to it so that it remains unknown. In addition, DCR is designed in a way that it also preserves the location privacy and anonymity of the source node as well as the communication anonymity. Unlike other anonymous routing protocols for ad hoc networks, DCR is based on the proactive as opposed to the reactive routing approach. We have instantiated DCR for various kinds of multihop ad hoc networks. For networks of type mesh and MANET, we have proposed three variations of our V-routing protoco...

American Journal of Advanced Scientific Research, Sep 22, 2013

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2011

The periodic mixed convection of a water–copper nanofluid inside a rectangular cavity with aspect... more The periodic mixed convection of a water–copper nanofluid inside a rectangular cavity with aspect ratio of 3 is investigated numerically. The temperature of the bottom wall of the cavity is assumed greater than the temperature of the top lid which oscillates horizontally with the velocity defined as u = u0 sin ( ωt). The effects of Richardson number, Ri, and volume fraction of nanoparticles on the flow and thermal behaviour of the nanofluid are investigated. Velocity, temperature profiles, and streamlines are presented. It is observed that when Ri < 1, heat transfer rate is much greater than when Ri > 1. The higher value of Ri corresponds to a lower value of the amplitude of the oscillation of Nu m in the steady periodic state. Moreover, increasing the volume fraction of the nanoparticles increases the heat transfer rate.

IFIP International Federation for Information Processing

In this paper, a routing protocol is proposed that provides location privacy for the source and t... more In this paper, a routing protocol is proposed that provides location privacy for the source and the destination as well as user anonymity and unlinkability in multihop wireless sensor networks. The sink is assumed to be computationally powerful and responsible for all routing decisions. It assigns incoming and outgoing labels to nodes in the uplink and downlink directions. Each node is only aware of its own labels and only forwards packets whose labels match either its downlink or uplink incoming label. Moreover, in order to prevent packet tracing by a global eavesdropper, layered cryptography is used in both directions to make a packet look randomly different on different links. However, due to the node capability limitations, only symmetric cryptography is used.

Proceedings of the 3rd ACM workshop on QoS and security for wireless and mobile networks - Q2SWinet '07, 2007

ABSTRACT Topology discovery in wireless sensor networks typically starts by transmitting a specia... more ABSTRACT Topology discovery in wireless sensor networks typically starts by transmitting a special beacon signal from the sink. This method, although simple and efficient, reveals the location of the sink within the network. We propose an anonymous topology discovery protocol ...

Heat Transfer Research, 2015

ABSTRACT Numerical investigation of flow and heat transfer around a long heated inclined square c... more ABSTRACT Numerical investigation of flow and heat transfer around a long heated inclined square cylinder placed in a horizontal plane channel in a steady laminar regime is carried out for the conditions: 1 ≤ Re ≤ 40, 0.7 ≤ Pr ≤ 100, inclination angle equal to 45° and blockage ratio to β = 1/8, 1/6, and 1/4. The streamlines and isotherms are presented to elucidate the effects of the channel confinement, Prandtl number, and two thermal boundary conditions (constant wall temperature, CWT, and uniform heat flux, UHF) on the physics of the problem. Generally, an increase in a blockage ratio increases the drag coefficient and decreases the wake length. The average Nusselt number also increases with Prandtl and/or Reynolds number. Furthermore, decreasing the blockage ratio decreases the dimensionless local pressure drop and increases the average Nusselt number for low Re and Pr numbers. This can be an economical result for improving the thermal efficiency of the problem. However, for larger Reynolds and Prandtl numbers the average Nusselt number and local pressure drop increase with the blockage ratio. Finally, some simple correlations are introduced for recirculation length, drag coefficient, dimensionless local pressure drop, and average Nusselt number at different blockage ratios.

European Journal of Mechanics - B/Fluids, 2015

Laminar forced convection heat transfer of water-Cu nanofluids in a microchannel was studied util... more Laminar forced convection heat transfer of water-Cu nanofluids in a microchannel was studied utilizing the lattice Boltzmann method (LBM). The entering flow was at a lower temperature compared to the microchannel walls. Simulations were performed for nanoparticle volume fractions of 0.00 to 0.04 and slip coefficient from 0.005 to 0.02. The model predictions were found to be in good agreement with earlier studies. The effects of wall slip velocity and temperature jump of the nanofluid were studied for the first time by using lattice Boltzmann method. Streamlines, isotherms, longitudinal variations of Nusselt number, slip velocity and temperature jump as well as velocity and temperature profiles for different cross sections were presented. The results indicate that LBM can be used to simulate forced convection for the nanofluid micro flows. Moreover, the effect of the temperature jump on the heat transfer rate is significant. Also, the results showed that decreasing the values of slip coefficient enhances the convective heat transfer coefficient and consequently the Nusselt number (Nu) but increases the wall slip velocity and temperature jump values.

Introduction: Nowadays, Geographic Information System (GIS) is considered as a main part of many ... more Introduction: Nowadays, Geographic Information System (GIS) is considered as a main part of many public health and epidemiological projects. The purpose of this study was to use GIS in presenting geographic distribution of pulmonary non-tuberculous Mycobacteria (PNTM) disease and identify environmental and socio-economic factors predictive of disease. Methods: PNTM cases from National Research Institute of Tuberculosis and Lung Disease (NRITLD) in three states (Khuzestan, Eastern Azarbayjan, Ghom), which have the highest prevalence of PNTM in country, were manually geocoded with permission of patients. Patients9 addresses were considered as locations, in which NTM exists. By Maxent model, other NTM presence locations in area of study were predicted and the relationship identified.Socio-economic factors and their relationship with patients were reflected in maps. Results: Response curves yield from Maxent approach for each environmental factor, showed that increasing in elevation and annual precipitation cause to decrease in NTM presence probability. Areas with greater temperature seasonality and also greater organic carbon seem to have greater probability of NTM presence. NTM can be found in soils with pH more than 5 and the chance of presence can increase in such environment. Contemplate of socio-economic factors showed that most of PNTM patients were residents of towns, had lower education and income level, and were older than 50 years old. Conclusion: GIS is a valuable tool in studying and analyzing incidence and prevalence of diseases because of its immense capabilities in gathering and preparing, and also analyzing data.

Thermal Science, 2009

A fully three-dimensional computational fluid dynamic model is used to analyze the mechanism of f... more A fully three-dimensional computational fluid dynamic model is used to analyze the mechanism of flow and heat transfer in a vortex tube. Vortex tube is a simple circular tube with interesting function and several industrial applications and contains one or more inlets and two outlets. It is used as a spot cooling device in industry. The past numerical investigations of vortex tube have been performed with the two-dimensional axisymmetric assumption but in the present work this problem is studied fully three-dimensional without making that assumption. Using this model, appropriate numerical results are presented to clarify physical understanding of the flow and energy separation inside the vortex tube. It is observed that there are considerable differences between the results of the two aforementioned models, and that the results of fully three-dimensional model are more accurate and agree better with available experimental data. Moreover, the parameters affecting the cooling efficie...

IFIP International Federation for Information Processing

An overlay routing protocol for infrastructure mesh networks is proposed that preserves user loca... more An overlay routing protocol for infrastructure mesh networks is proposed that preserves user location privacy, source anonymity, destination anonymity and communication anonymity against an omnipresent eavesdropper, when the underlying routing protocol is based on a proactive approach. A client only trusts its immediate access router. In order to receive packets, a client establishes a secret hop-by-hop virtual circuit between an arbitrary router, called its Rendezvous Point (RP) and its own access router, ahead of time. Packets destined for that client would be sent to RP first. To thwart content analysis attacks, we have used per-hop encryption. Authenticity and confidentiality of exchanged messages are also ensured using a public key infrastructure (PKI).

6th Annual Communication Networks and Services Research Conference (cnsr 2008), 2008

The overhead of periodic routing updates in proactive routing protocols has been always the main ... more The overhead of periodic routing updates in proactive routing protocols has been always the main impediment in the way of using this kind of protocols in wireless ad hoc networks specially sensor networks. In this paper, we introduce a new topology discovery protocol based on ...

Indian Journal of Rheumatology, 2014

Telecommunication Systems, 2008

In the era of "anywhere, anytime communication", contextual security is becoming very important. ... more In the era of "anywhere, anytime communication", contextual security is becoming very important. Context security means preventing leakage of information about such aspects of communication as identities of the parties involved, their locations, frequency and the times of communications, and so on as opposed to content security which is concerned with protecting the transmitted data against eavesdropping and manipulation and is usually achieved using encryption and message digests. Routing protocols play an important role in this regard. All of the previously proposed solutions in this area are based on reactive routing. In this paper, we propose a solution called V-routing based on proactive routing protocols for ad hoc networks of the type Mesh 1 and MANET that conceals the locations and the identities of the communicating parties as well as the fact that they are communicating. Our protocol resists an omnipresent eavesdropper that tries to locate and identify the source and the destination of a data flow. V-routing is especially capable of hiding the destination, unlike many other 1 V-routing for mesh networks was first proposed in [29].

Journal of Non-Newtonian Fluid Mechanics, 2011

The incompressible Poiseuille flow and heat transfer of a power-law fluid across an inclined long... more The incompressible Poiseuille flow and heat transfer of a power-law fluid across an inclined long square cylinder confined in a two-dimensional channel is investigated numerically in the steady laminar flow regime. The effects of inclination angle, α, and power-law index, n, on the non-dimensional pumping power and the Nusselt number are studied for the conditions: 1⩽Re⩽40, 0⩽α⩽45, 0.4⩽n⩽1.8, Pr=50 and

International Journal of Thermal Sciences, 2012

International Journal of Refrigeration, 2010

In this paper, the effects of the nozzles number on the flow and power of cooling of a vortex tub... more In this paper, the effects of the nozzles number on the flow and power of cooling of a vortex tube are studied, using a three-dimensional numerical fluid dynamic model. Vortex tube has interesting functions and several industrial applications, and, as a refrigerator, it is used as a spot cooling device in industry. High-pressure compressible fluid enters the vortex tube and leaves its cold and hot outlets at lower and higher temperatures than that of the inlet flow, respectively. A few experimental and a fewer numerical studies have been conducted in recent years on the effects of nozzles number of a vortex tube. However, in this paper, the effects of nozzles number on the flow and power of cooling of a counterflow vortex tube are investigated comprehensively. It is observed that as the number of nozzles is increased, power of cooling increases significantly while cold outlet temperature decreases moderately.

Computer Networks, 2008

In this paper, k-anonymity notion is adopted to be used in wireless sensor networks (WSN) as a se... more In this paper, k-anonymity notion is adopted to be used in wireless sensor networks (WSN) as a security framework with two levels of privacy. A base level of privacy is provided for the data shared with semitrusted sink and a deeper level of privacy is provided against eavesdroppers. In the proposed method, some portions of data are encrypted and the rest is generalized. Generalization shortens the size of the data transmitted in the network causing energy saving at the cost of information loss. On the other hand, encryption provides anonymization with no information loss and without saving energy. Thus, there is a tradeoff between information loss and energy saving. In our system, this tradeoff is intelligently managed by a system parameter, which adjusts the amount of data portions to be encrypted. We use a method based on bottom up clustering that chooses the data portions to be encrypted among the ones that cause maximum information loss when generalized. In this way, a high degree of energy saving is realized within the given limits of information loss. Our analysis shows that the proposed method achieves the desired privacy levels with low information loss and with considerable energy saving.

Applied Thermal Engineering, 2011

Anonymity and location privacy are two important aspects of network security for users. This thes... more Anonymity and location privacy are two important aspects of network security for users. This thesis is concerned with location privacy and anonymity in multihop wireless ad hoc networks. More specifically, it proposes techniques to protect these features from being violated as a by-product of ad hoc routing protocols. We have proposed a novel destination-centric routing approach called Destination Controlled Routing (DCR) in which the destination is the master and controls how packets are delivered to it so that it remains unknown. In addition, DCR is designed in a way that it also preserves the location privacy and anonymity of the source node as well as the communication anonymity. Unlike other anonymous routing protocols for ad hoc networks, DCR is based on the proactive as opposed to the reactive routing approach. We have instantiated DCR for various kinds of multihop ad hoc networks. For networks of type mesh and MANET, we have proposed three variations of our V-routing protoco...

American Journal of Advanced Scientific Research, Sep 22, 2013

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2011

The periodic mixed convection of a water–copper nanofluid inside a rectangular cavity with aspect... more The periodic mixed convection of a water–copper nanofluid inside a rectangular cavity with aspect ratio of 3 is investigated numerically. The temperature of the bottom wall of the cavity is assumed greater than the temperature of the top lid which oscillates horizontally with the velocity defined as u = u0 sin ( ωt). The effects of Richardson number, Ri, and volume fraction of nanoparticles on the flow and thermal behaviour of the nanofluid are investigated. Velocity, temperature profiles, and streamlines are presented. It is observed that when Ri < 1, heat transfer rate is much greater than when Ri > 1. The higher value of Ri corresponds to a lower value of the amplitude of the oscillation of Nu m in the steady periodic state. Moreover, increasing the volume fraction of the nanoparticles increases the heat transfer rate.

IFIP International Federation for Information Processing

In this paper, a routing protocol is proposed that provides location privacy for the source and t... more In this paper, a routing protocol is proposed that provides location privacy for the source and the destination as well as user anonymity and unlinkability in multihop wireless sensor networks. The sink is assumed to be computationally powerful and responsible for all routing decisions. It assigns incoming and outgoing labels to nodes in the uplink and downlink directions. Each node is only aware of its own labels and only forwards packets whose labels match either its downlink or uplink incoming label. Moreover, in order to prevent packet tracing by a global eavesdropper, layered cryptography is used in both directions to make a packet look randomly different on different links. However, due to the node capability limitations, only symmetric cryptography is used.

Proceedings of the 3rd ACM workshop on QoS and security for wireless and mobile networks - Q2SWinet '07, 2007

ABSTRACT Topology discovery in wireless sensor networks typically starts by transmitting a specia... more ABSTRACT Topology discovery in wireless sensor networks typically starts by transmitting a special beacon signal from the sink. This method, although simple and efficient, reveals the location of the sink within the network. We propose an anonymous topology discovery protocol ...

Heat Transfer Research, 2015

ABSTRACT Numerical investigation of flow and heat transfer around a long heated inclined square c... more ABSTRACT Numerical investigation of flow and heat transfer around a long heated inclined square cylinder placed in a horizontal plane channel in a steady laminar regime is carried out for the conditions: 1 ≤ Re ≤ 40, 0.7 ≤ Pr ≤ 100, inclination angle equal to 45° and blockage ratio to β = 1/8, 1/6, and 1/4. The streamlines and isotherms are presented to elucidate the effects of the channel confinement, Prandtl number, and two thermal boundary conditions (constant wall temperature, CWT, and uniform heat flux, UHF) on the physics of the problem. Generally, an increase in a blockage ratio increases the drag coefficient and decreases the wake length. The average Nusselt number also increases with Prandtl and/or Reynolds number. Furthermore, decreasing the blockage ratio decreases the dimensionless local pressure drop and increases the average Nusselt number for low Re and Pr numbers. This can be an economical result for improving the thermal efficiency of the problem. However, for larger Reynolds and Prandtl numbers the average Nusselt number and local pressure drop increase with the blockage ratio. Finally, some simple correlations are introduced for recirculation length, drag coefficient, dimensionless local pressure drop, and average Nusselt number at different blockage ratios.

European Journal of Mechanics - B/Fluids, 2015

Laminar forced convection heat transfer of water-Cu nanofluids in a microchannel was studied util... more Laminar forced convection heat transfer of water-Cu nanofluids in a microchannel was studied utilizing the lattice Boltzmann method (LBM). The entering flow was at a lower temperature compared to the microchannel walls. Simulations were performed for nanoparticle volume fractions of 0.00 to 0.04 and slip coefficient from 0.005 to 0.02. The model predictions were found to be in good agreement with earlier studies. The effects of wall slip velocity and temperature jump of the nanofluid were studied for the first time by using lattice Boltzmann method. Streamlines, isotherms, longitudinal variations of Nusselt number, slip velocity and temperature jump as well as velocity and temperature profiles for different cross sections were presented. The results indicate that LBM can be used to simulate forced convection for the nanofluid micro flows. Moreover, the effect of the temperature jump on the heat transfer rate is significant. Also, the results showed that decreasing the values of slip coefficient enhances the convective heat transfer coefficient and consequently the Nusselt number (Nu) but increases the wall slip velocity and temperature jump values.

Introduction: Nowadays, Geographic Information System (GIS) is considered as a main part of many ... more Introduction: Nowadays, Geographic Information System (GIS) is considered as a main part of many public health and epidemiological projects. The purpose of this study was to use GIS in presenting geographic distribution of pulmonary non-tuberculous Mycobacteria (PNTM) disease and identify environmental and socio-economic factors predictive of disease. Methods: PNTM cases from National Research Institute of Tuberculosis and Lung Disease (NRITLD) in three states (Khuzestan, Eastern Azarbayjan, Ghom), which have the highest prevalence of PNTM in country, were manually geocoded with permission of patients. Patients9 addresses were considered as locations, in which NTM exists. By Maxent model, other NTM presence locations in area of study were predicted and the relationship identified.Socio-economic factors and their relationship with patients were reflected in maps. Results: Response curves yield from Maxent approach for each environmental factor, showed that increasing in elevation and annual precipitation cause to decrease in NTM presence probability. Areas with greater temperature seasonality and also greater organic carbon seem to have greater probability of NTM presence. NTM can be found in soils with pH more than 5 and the chance of presence can increase in such environment. Contemplate of socio-economic factors showed that most of PNTM patients were residents of towns, had lower education and income level, and were older than 50 years old. Conclusion: GIS is a valuable tool in studying and analyzing incidence and prevalence of diseases because of its immense capabilities in gathering and preparing, and also analyzing data.

Thermal Science, 2009

A fully three-dimensional computational fluid dynamic model is used to analyze the mechanism of f... more A fully three-dimensional computational fluid dynamic model is used to analyze the mechanism of flow and heat transfer in a vortex tube. Vortex tube is a simple circular tube with interesting function and several industrial applications and contains one or more inlets and two outlets. It is used as a spot cooling device in industry. The past numerical investigations of vortex tube have been performed with the two-dimensional axisymmetric assumption but in the present work this problem is studied fully three-dimensional without making that assumption. Using this model, appropriate numerical results are presented to clarify physical understanding of the flow and energy separation inside the vortex tube. It is observed that there are considerable differences between the results of the two aforementioned models, and that the results of fully three-dimensional model are more accurate and agree better with available experimental data. Moreover, the parameters affecting the cooling efficie...

IFIP International Federation for Information Processing

An overlay routing protocol for infrastructure mesh networks is proposed that preserves user loca... more An overlay routing protocol for infrastructure mesh networks is proposed that preserves user location privacy, source anonymity, destination anonymity and communication anonymity against an omnipresent eavesdropper, when the underlying routing protocol is based on a proactive approach. A client only trusts its immediate access router. In order to receive packets, a client establishes a secret hop-by-hop virtual circuit between an arbitrary router, called its Rendezvous Point (RP) and its own access router, ahead of time. Packets destined for that client would be sent to RP first. To thwart content analysis attacks, we have used per-hop encryption. Authenticity and confidentiality of exchanged messages are also ensured using a public key infrastructure (PKI).

6th Annual Communication Networks and Services Research Conference (cnsr 2008), 2008

The overhead of periodic routing updates in proactive routing protocols has been always the main ... more The overhead of periodic routing updates in proactive routing protocols has been always the main impediment in the way of using this kind of protocols in wireless ad hoc networks specially sensor networks. In this paper, we introduce a new topology discovery protocol based on ...

Indian Journal of Rheumatology, 2014

Telecommunication Systems, 2008

In the era of "anywhere, anytime communication", contextual security is becoming very important. ... more In the era of "anywhere, anytime communication", contextual security is becoming very important. Context security means preventing leakage of information about such aspects of communication as identities of the parties involved, their locations, frequency and the times of communications, and so on as opposed to content security which is concerned with protecting the transmitted data against eavesdropping and manipulation and is usually achieved using encryption and message digests. Routing protocols play an important role in this regard. All of the previously proposed solutions in this area are based on reactive routing. In this paper, we propose a solution called V-routing based on proactive routing protocols for ad hoc networks of the type Mesh 1 and MANET that conceals the locations and the identities of the communicating parties as well as the fact that they are communicating. Our protocol resists an omnipresent eavesdropper that tries to locate and identify the source and the destination of a data flow. V-routing is especially capable of hiding the destination, unlike many other 1 V-routing for mesh networks was first proposed in [29].

Journal of Non-Newtonian Fluid Mechanics, 2011

The incompressible Poiseuille flow and heat transfer of a power-law fluid across an inclined long... more The incompressible Poiseuille flow and heat transfer of a power-law fluid across an inclined long square cylinder confined in a two-dimensional channel is investigated numerically in the steady laminar flow regime. The effects of inclination angle, α, and power-law index, n, on the non-dimensional pumping power and the Nusselt number are studied for the conditions: 1⩽Re⩽40, 0⩽α⩽45, 0.4⩽n⩽1.8, Pr=50 and

International Journal of Thermal Sciences, 2012

International Journal of Refrigeration, 2010

In this paper, the effects of the nozzles number on the flow and power of cooling of a vortex tub... more In this paper, the effects of the nozzles number on the flow and power of cooling of a vortex tube are studied, using a three-dimensional numerical fluid dynamic model. Vortex tube has interesting functions and several industrial applications, and, as a refrigerator, it is used as a spot cooling device in industry. High-pressure compressible fluid enters the vortex tube and leaves its cold and hot outlets at lower and higher temperatures than that of the inlet flow, respectively. A few experimental and a fewer numerical studies have been conducted in recent years on the effects of nozzles number of a vortex tube. However, in this paper, the effects of nozzles number on the flow and power of cooling of a counterflow vortex tube are investigated comprehensively. It is observed that as the number of nozzles is increased, power of cooling increases significantly while cold outlet temperature decreases moderately.

Computer Networks, 2008

In this paper, k-anonymity notion is adopted to be used in wireless sensor networks (WSN) as a se... more In this paper, k-anonymity notion is adopted to be used in wireless sensor networks (WSN) as a security framework with two levels of privacy. A base level of privacy is provided for the data shared with semitrusted sink and a deeper level of privacy is provided against eavesdroppers. In the proposed method, some portions of data are encrypted and the rest is generalized. Generalization shortens the size of the data transmitted in the network causing energy saving at the cost of information loss. On the other hand, encryption provides anonymization with no information loss and without saving energy. Thus, there is a tradeoff between information loss and energy saving. In our system, this tradeoff is intelligently managed by a system parameter, which adjusts the amount of data portions to be encrypted. We use a method based on bottom up clustering that chooses the data portions to be encrypted among the ones that cause maximum information loss when generalized. In this way, a high degree of energy saving is realized within the given limits of information loss. Our analysis shows that the proposed method achieves the desired privacy levels with low information loss and with considerable energy saving.

Applied Thermal Engineering, 2011