82 research outputs found
Investigation of a mechatronic device for the remedial treatment of brain injured children.
To speed the recovery of brain injured children using the method of patterning; it must be made efficient. Efficiency can be achieved by automating the manual method, which will provide the patients with the necessary stimuli needed to help them enhance/restore their natural mobility.
This thesis describes research into a novel moderate-cost single-axis Mechatronics device for the remedial treatment of brain injured patients. The device will enhance and/or improve their natural mobility by stimulating the undamaged brain cells responsible for mobility in the central nervous system through physical activity.
A detailed review of rehabilitation robotics was undertaken, covering more than seventy projects relating to disabled people. This review helped to identify the main areas of this research regarding the most suitable structure of the machine and setting up the design specifications for the device. A critical investigation of past and present patterning machines and workstations helped avoid the mistakes made by previous designers in not including brain-injured patients in the initial stages of the design. Use of high technology video equipment has made practicable the development of mathematical expressions based on experimental data for the movements of human arms, feet and head.
Measurements taken and ergonomic data used made it possible to implement a realistic practical novel kinematic arrangement for the patterning machine. A thorough review of direct drive electrical actuators, and surveys and measurements of the human body with respect to the kinematic arrangements, resulted in the selection of the most appropriate actuator for each axis. The selection of the motor and gearbox was based on the mass of each part of the human body in the prone position, the criteria of high peak torque to motor ratio, low cost, minimum maintenance, safety and compatibility.
A computer model of the kinematic arrangement designed was created including the necessary motion constrains, using ADAMS and 3D Working Model simulation packages to test, verify and analyse the static and dynamic stability of the kinematic arrangements and the force interaction between the system and the patient. The simulation results led to some modification in the design regarding the kinematics and dynamic stability of the system by varying different design variables. A walking model of a human was created to simulate the real patient. The model was placed on two units where the feet were the only contact points with the moving belts; the model torso was supported by a harness to hold it in the upright standing position. The results obtained showed the movements of both feet (knees. hips and ankles) in addition to the right and left elbows.
The system hardware was designed and implemented using custom-made safety critical software to control the device to carry out the desired tasks. Safety is considered to be one of the main issues that this research program has developed and implemented. An optimal control strategy was developed to drive the prototype. Smooth movements of the system were achieved through a PD control system enhanced with velocity feed forward gain with position accuracy of ± 0.168 mm. The desired positional accuracy of the Patterner Machine was ± 0.632 mm
Novel group handover mechanism for cooperative and coordinated mobile femtocells technology in railway environment
Recently, the Mobile Femto (MF) Technology has been debated in many research papers to be a promising solution that will dominate future networks. This small cell technology plays a major role in supporting and maintaining network connectivity, enhancing the communication service as well as user experience for passengers in High-Speed Trains (HSTs) environments. Within the railway environment, there are many MF Technologies placed on HSTs to enhance the train passengers’ internet experience. Those users are more affected by the high penetration loss, path loss, dropped signals, and the unnecessary number of Handovers (HOs). Therefore, it is more appropriate to serve those mobile users by the in-train femtocell technology than being connected to the outside Access Points (APs) or Base Stations (BSs). Hence, having a series of MFs (called Cooperative and Coordinated MFs -CCMF) installed inside the train carriages has been seen to be a promising solution for train environments and future networks. The CCMF Technologies establish Backhaul (BH) links with the serving mother BS (DeNB). However, one of the main drawbacks in such an environment is the frequent and unnecessary number of HO procedures for the MFs and train passengers. Thus, this paper proposes an efficient Group HO mechanism that will improve signal connection and mitigate the impact of a signal outage when train carriages move from one serving cell to another. Unlike most work that uses Fixed Femtocell (FF) architecture, this work uses MF architecture. The achieved results via Matlab simulator show that the proposed HO scheme has achieved less outage probability of 0.055 when the distance between the MF and mobile users is less than 10 m compared to the signal outage probability of the conventional HO scheme. More results have shown that the dropping calls probability has been reduced when mobile users are connected to the MF compared to the direct transmission from the eNB. That is in turn has have improved the call duration of mobile UEs and reduced the dropping calls probability for mobile users who are connected to the MF compared to eNB direct connection UEs
Security and QoS integration for protecting service providers in hterogeneous environments
Similar to the Internet, connectivity in Next Generation
Networks such as 4G will be IP-Based. This implies
that they inherit all the security problems of the current
Internet. Amongst these numerous threats, compromise and
resource exhaustion threats which come in the form of Denial
of Service attacks, are very common and particularly serious.
The severity of such attacks will be fuelled by the development
of heterogeneous devices which have several wireless interfaces,
as multi-homed devices will be able to send multiple connection
requests to the server and thus launch attacks over different
access networks. This paper details a new model to address
the problem of Denial of Service attacks against the current
Internet which limit the accessibility of a server based on its
operational scope such that the solution will work effectively in
heterogeneous, multi-homed environments. However, Denial of
service attacks target the system resources and degrade their
performance thus, affecting the Quality of Service’s delivery to
the subscribed users. Therefore, the proposed model suggests
dealing with security and QoS in an integrated manner by
using the concept of Quality of Security Service where security
is considered as a Quality of Service’ parameter. This paper
furthermore shows how security can be integrated into the
infrastructure of future network systems. However, in order
to implement the proposed model, it is necessary to enhance
current networking infrastructure by extending current services
such as the Domain Naming Service and evolving new services
such as a Master Locator to support user mobility
A novel scheduling algorithm for improved performance of multi-objective safety-critical WSN using spatial self-organizing feature map
Technological advances in the internet of things (IoT) allowed a low-cost, yet small sensor device to operate with limited power in a dynamic harsh environment where human intervention is impossible. The wireless sensor network (WSN) is an example of the IoT in which physical devices’ software and sensors can interconnect to provide application services. It is important that such applications be dependable to meet the required quality of service (QoS) and function as expected. Consequently, the multi-objective optimization (MOO) problem in WSNs aims to address the trade-off among coverage, connectivity, and network lifetime requirements. Node scheduling is one approach of many used to optimize energy in WSNs. The contribution of this work is the proposal of a self-organizing feature map (SOFM) to enhance the node scheduling in WSNs. The proposed SOFM node-scheduling algorithm aims to spatially explore the state space domain and obtain an optimal solution. In our experiment, the proposed SOFM node-scheduling algorithm is evaluated against a comparable algorithm, namely the BAT node-scheduling algorithm, via MATLAB simulator. The results showed that the SOFM node-scheduling algorithm outperformed the latter by 27% and 28% for the maximum and minimum coverage, respectively, with similar performance of 99% of connectivity and network lifetime
Performance evaluation of wireless IEEE 802.11(b) used for ad-hoc networks in an e-learning classroom network
Evaluation of wireless networks for performance evaluation is a popular research area and a wealth of literature exists in this area. Wireless networks in infrastructure mode as well as Ad-hoc networks such as MANETs are considered extensively. Simulation results are provided for E-learning scenarios for cases where wireless networks in infrastructure mode are employed, however the possibilities of using ad- hoc networks and performance evaluation of e-learning scenarios with ad hoc networks are not considered. This paper presents an evaluation of the performances for wireless Ad-hoc networks employed in typical e-learning environment by using the OPNET modeller. Numerical simulation results, discussions and comparisons are provided. The results can be of great help for optimisation studies in typical e-learning environments. The performance issues are considered together with scalability concerns
Introducing mobile home agents into the distributed authentication protocol to achieve location privacy in mobile IPv6
Mobile IPv6 will be the basis for the fourth generation 4G networks which will completely revolutionize the way telecommunication devices operate. This paradigm shift will occur due to the sole use of packed switching networks. Mobile IPv6 utilizes binding updates as a route optimization to reduced triangle routing between the mobile node, the home agent and the correspondent node, allowing direct communication between the mobile node and the correspondent. However, direct communication between the nodes produces a range of security vulnerabilities, which the home agent avoided. This paper attempts to provide the advantages of using the home agent as an intermediary whilst reducing the latency of triangle routing. This can be achieved with the proposed use of a mobile home agent which essentially follows the mobile node as it moves between points of attachment providing location privacy and pseudo-direct communication, which can be incorporated into the distributed authentication protocol or be used as a stand alone solution
Cooperative and coordinated Mobile Femtocells technology in high-speed vehicular environments: mobility and interference management
In future networks, most users who will be accessing wireless broadband will be vehicular. Serving those users cost-effectively and improving their signal quality has been the main concern of many studies. Thus, the deployment of Mobile Femtocell (Mobile-Femto) technology on public transportation is seen to be one of the promising solutions. Mobile-Femto comes with its mobility and interference challenges. Therefore, eliminating the Vehicular Penetration Loss (VPL) and interference while improving signal quality and mobility for train passengers is the main concern of this paper. The initial system-level evaluation showed that the dedicated Mobile-Femto deployment has great potential in improving users’ experience inside public transportation. The Downlink (DL) results of the Proposed Interference Management Scheme (PIMS) showed significant improvement in Mobile-Femto User Equipment (UE) gains (up to 50%) without impacting the performance of macro UEs. In contrast, the Uplink (UL) results showed noticeable gains for both macro UEs and Mobile-Femto UEs
Mobility management for vehicular user equipment in LTE/mobile femtocell networks
Vehicular User Equipment (UE) performance during mobility faces two issues relating to signaling and transmission, namely Handover (HO) and link adaptation. This paper shows that both processes are experiencing degradation during mobility and that vehicular UEs suffer from call drops and loss of connections. Therefore, this work presents an effective technique using Mobile-Femtos to improve vehicular UEs' HO process and link quality. Results show that vehicular UEs attached to a Mobile-Femto achieved better signalling and Link Ergodic capacity and as a consequence the outage probability was reduced. The achieved results indicated that deploying Mobile-Femtos under 25dB Vehicular Penetration Loss (VPL) has improved the vehicular UE Link Ergodic capacity by 1% and reduced the signal outage probability by 1.8% compared to the eNB direct transmission. Consequently, Drop Calls Probability (DCP) and Block Calls Probability (BCP) have been reduced by 7% and 14% respectively compared to the direct transmission from the eNB
Interference management for co-channel mobile femtocells technology in LTE networks
The dense deployment of Femtocells within the Macrocell's coverage is expected to dominate the future of Long Term Evolution (LTE) networks. While Mobile Femtocells (Mobile-Femtos) could be the solution for vehicular networks when there is a need to improve the vehicular User Equipment (UE) performance by mitigating the impact of penetration loss and path-loss issues. The deployed Femtocells have operated in a co-channel deployment due to the scarcity of spectrums. This issue causes interference between Femtocells and Macrocells as well it causes extra overhead on the LTE networks because of the co-tire interference between adjacent Femtocells. In this paper two interference scenarios are considered, the interference between Mobile-Femto and Macrocell, and the interference between the Mobile Femtos themselves. Therefore, to avoid the generated interference between Femtocells, the controlled transmission powers as well as the coverage planning techniques have been discussed. While in the worst-case scenarios, a frequency reuse scheme has been proposed to avoid the generated interference effectively and dynamically between the Mobile-Femtos as well as their UEs and between the Macrocell UEs
A novel scheduling algorithm for improved performance of multi-objective safety-critical wireless sensor networks using long short-term memory
The multiple objective optimisation (MOO) challenges encountered in the context of wireless sensor networks (WSNs) present a formidable NP-hard problem. These issues primarily arise from the constraints imposed by critical factors such as connectivity, coverage, and, most notably, energy consumption. Simultaneously fulfilling these three requirements is no longer considered the standard approach for enhancing system dependability. To illustrate, a prospective solution may optimise one or two of these requirements while bolstering overall network energy efficiency. Nonetheless, prior endeavours documented in the extant literature reveal unexplored avenues for enhancement. Hence, this paper introduces a new methodology aimed at alleviating MOO concerns and thereby enhancing the quality of service (QoS) in WSNs. A long short-term memory (LSTM) model is proposed as an analytical tool to deliver an energy-efficient scheduling solution that aligns and optimises WSN parameters, striving to attain the most favourable system performance. The LSTM algorithm’s effectiveness is assessed through the iterative application of periods, confirming the desired QoS levels. The unique feature of LSTM lies in its capability to observe specific event sequences and subsequently establish them as the system’s default configuration for its entire operational lifespan. Once these favourable parameters are identified, LSTM automatically ensures consistent service availability and reliability throughout the network’s lifespan. The results obtained demonstrate the superiority of the proposed LSTM-based scheduling algorithm in comparison to the self-organising map (SOFM)-based node scheduling algorithm. The LSTM-based approach outperforms the SOFM-based alternative by a remarkable 75% in terms of coverage and exhibits a 20% enhancement in network lifetime, all while maintaining equivalent levels of connectivity (i.e., 99%) in both algorithms
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