1,721,224 research outputs found
Design of knee joint mechanisms and in-socket sensors for transfemoral amputees / Amr Mohammed El-Sayed Ahmed
Full text linkLower limb prostheses are developed to assist amputees in restoring mobility functions such as walking, sit-to-stand, stair ascent/descent, and ramp climbing. Although the current prostheses are equipped with sensors, actuators, controllers, and mechanical structures, they require improvements to mimic the function of the natural limbs. The first challenge in prosthetic development is to monitor the amputee/prosthesis interaction by using sensors built into the socket. This interaction helps in detecting the gait phases and events, in addition to develop new control strategies for prostheses, which may enhance the amputees’ comfort. The second challenge is to develop a knee prosthetic mechanism that could imitate the functions of the natural knee.
To accomplish the aims of this thesis, studies were undertaken consecutively. First, the technology of the knee prosthesis was studied to understand the functionality of its components. The technology review showed that the sensory system requires enhancement, in particular, a new sensory system can be added-on to the mechanical sensors to sense the user’s intent, identify the transition between phases, and improve the control performance of the prosthesis. Based on this study, the piezoelectric bimorph (PB) was selected as the sensing element while a linear motor was selected as the most appropriate actuator.
Next, the PB was validated as a sensing element by finding out its characteristics for the intended application. The static and dynamic characteristics of the PB were investigated and tested as an in-socket sensor with a transfemoral amputee to check its ability to sense the movement of the knee prosthesis. Moreover, the PB was tested as an actuation element in an application named microgripper that was capable of grasping a small object. Also, the PB was compared with a force sensitive resistor (FSR) as an in-socket sensor for a transfemoral amputee performing activities such as walking, sit-to-stand, and stair climbing. The PB could track the knee angle at most of the activities, while the FSR could be used as a trigger sensor at different movements.
In the second stage, the focus was on the actuation system and mechanical structure of the knee prosthesis. It was found that, the mechanical actuation system needs improvement in terms of the normal range of motion and the power generation in activities that require extra torque and power. Therefore, a new design of knee prosthesis mechanism that contains a linear actuation system was presented and modeled using a physical modelling tool. The mechanism was physically simulated and controlled using PID controller at activities of daily living (ADL). Finally, an overall control framework of the knee mechanism using in-socket sensor was presented to guide the researchers to develop a knee prosthesis that could be controlled using in-socket sensors.
In conclusion, the study demonstrates the possibility of using the piezoelectric bimorph as an in-socket transducer. Furthermore, a knee prosthesis mechanism was successfully designed, modelled, and tested at ADL. Further, clinical trials are recommended for the knee mechanism upon future development. Moreover, more subjects with different types of sockets may be tested towards improving the functionality of the knee prosthesi
Disability Assistant System Using Brain-Computer Interface and EEG Signals
No full textObjects' telepathic control letting people use their minds to move objects telepathically has always been a part of fictional movies and literature. Nowadays, this fictional interpretation is becoming our reality. BrainComputer Interface (BCI) provides the power that enables people with disabilities to interact with their environment. BCI obtains brain activity measured through different techniques like the EEG signals. These signals can be extracted, enhanced, analyzed, and sent to computers for processing and translated to several physical commands. These commands can be transferred to output devices to apply the actions. People suffering from neuromuscular problems or disorders can use brain signals to communicate and handle objects in their environment, which allows them to do activities they cannot do due to disabilities. The neurons are the fundamental unit of the brain and nervous system. When thinking, moving, or feeling, these neurons will be activated and can be represented by electrical impulses and biochemical signals. In this work, the EEG signals will be captured and recorded using EMOTIV Insight 2.0 headset. The processed signals from each user will be utilized to train a customized user-specific profile to interpret these use's signals into physical computer commands. These interpreted commands will be sent to the object under control (a robot in this experiment) to manage the object's activities. Also, face and eye muscles activities will be used in fusion with the EEG signals to enhance the performance metrics and improve the controllability of the device under control. A non-holonomic differential drive robot will be used as the object under control in this work. The robot can be replaced by a wheelchair, scooter, or any other medical device that patients with disabilities require
Supplemental Material - Potential diagnostic role of circulating MiRNAs in colorectal cancer
No full textSupplemental Material for Potential diagnostic role of circulating MiRNAs in colorectal cancer by Dina A El-Sayed, Ahmed MH Salem, Menha M Swellam and Marwa GA Hegazy in International Journal of Immunopathology and Pharmacology</p
Interview with Ahmed El-Sayed Ahmed
No full textمقابلة مع زير المواصلات في جمهورية السودان، الدكتور أحمد السيد حمد، يناقش فيها التطويرات والتجديدات في مجال المواصلات والإتصالات في السودان. ويتحدث عن خطط المشاريع التي تتعاون في تمويلها بلاد مثل ألمانيا وفرنسا. قام بالمقابلة إبراهيم عابدين.An interview with the Sudanese Minister of Transportation, Dr. Ahmed El-Sayed Hamad, in which he discusses developments and innovations in the field of transportation and communications in Sudan. He also speaks in which he discusses plans for developmental projects that are co-financed by countries such as Germany and France. The interview was conducted by Ibrahim Abdeen
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
