Spatial coordinated medium sharing: Optimal access control management in drive-thru internet

Driven by the ever-growing expectation of ubiquitous connectivity and the widespread adoption of IEEE 802.11 networks, it is not only highly demanded but also entirely possible for in-motion vehicles to establish convenient Internet access to roadside WiFi access points (APs) than ever before, which is referred to as Drive-Thru Internet. The performance of Drive-Thru Internet, however, would suffer from the high vehicle mobility, severe channel contentions, and instinct issues of the IEEE 802.11 MAC as it was originally designed for static scenarios. As an effort to address these problems, in this paper, we develop a unified analytical framework to evaluate the performance of Drive-Thru Internet, which can accommodate various vehicular traffic flow states, and to be compatible with IEEE 802.11a/b/g networks with a distributed coordination function (DCF). We first develop the mathematical analysis to evaluate the mean saturated throughput of vehicles and the transmitted data volume of a vehicle per drive-thru. We show that the throughput performance of Drive-Thru Internet can be enhanced by selecting an optimal transmission region within an AP's coverage for the coordinated medium sharing of all vehicles. We then develop a spatial access control management approach accordingly, which ensures the airtime fairness for medium sharing and boosts the throughput performance of Drive-Thru Internet in a practical, efficient, and distributed manner. Simulation results show that our optimal access control management approach can efficiently work in IEEE 802.11b and 802.11g networks. The maximal transmitted data volume per drive-thru can be enhanced by 113.1% and 59.5% for IEEE 802.11b and IEEE 802.11g networks with a DCF, respectively, compared with the normal IEEE 802.11 medium access with a DCF.

ChainCluster : engineering a cooperative content distribution framework for highway vehicular communications

The recent advances in wireless communication techniques have made it possible for fast-moving vehicles to download data from the roadside communications infrastructure [e.g., IEEE 802.11b Access Point (AP)], namely, Drive-thru Internet. However, due to the high mobility, harsh, and intermittent wireless channels, the data download volume of individual vehicle per drive-thru is quite limited, as observed in real-world tests. This would severely restrict the service quality of upper layer applications, such as file download and video streaming. On addressing this issue, in this paper, we propose ChainCluster, a cooperative Drive-thru Internet scheme. ChainCluster selects appropriate vehicles to form a linear cluster on the highway. The cluster members then cooperatively download the same content file, with each member retrieving one portion of the file, from the roadside infrastructure. With cluster members consecutively driving through the roadside infrastructure, the download of a single vehicle is virtually extended to that of a tandem of vehicles, which accordingly enhances the probability of successful file download significantly. With a delicate linear cluster formation scheme proposed and applied, in this paper, we first develop an analytical framework to evaluate the data volume that can be downloaded using cooperative drive-thru. Using simulations, we then verify the performance of ChainCluster and show that our analysis can match the simulations well. Finally, we show that ChainCluster can outperform the typical studied clustering schemes and provide general guidance for cooperative content distribution in highway vehicular communications.

Nonlinear identification of pneumatic servo-drive

Three nonlinear approaches to model the nonlinear pneumatic servo- drive are presented. The three nonlinear approaches are: (1) the multi input-single output (MISO) approach, which describes the single input-single output (SISO) nonlinear plant using a MISO linear representation which allows replacement of the nonlinear analysis by a linear one without approximation, and is studied in both time and frequency domains; (2) piecewise linearization, which systematically replaces, using artificial neural network, the nonlinear surface representing the plant in the hyper input-output space by a number of linear planes that are continuous over the boundaries between them; and (3) Adaptive Neuro-Fuzzy Inference System (ANFIS), in which the fuzzy rules are placed in a neural network structure, and which consequently utilizes neural networks learning rules to systematically tune the nonlinear fuzzy model. The superiority of these nonlinear models over the best model that can be developed using linear identification techniques is shown.

Mobile healthcare information systems : thru' the ant lens

Deployment of mobile technologies and applications in health care are becoming prevalent worldwide. As mobile innovation and standards in wireless continue to evolve, so does the mobile health care information systems framework. In this paper, we explore this evolving framework by synthesising current technologies, applications, issues and examining this through the actor-network theory (ANT) which seeks to understand socio-technical change by adopting a symmetric treatment of people and technologies.

Appearance-based comments, body dissatisfaction and drive for muscularity in males

This study examined the role of positive and negative appearance-based comments on body dissatisfaction and drive for muscularity among young adult males. The direct and moderating effect of self-esteem were also investigated; and BMI, age, and social desirability were included as covariates. The participants were 214 males aged between 18 and 30 years. More frequent negative comments were associated with higher body dissatisfaction whilst more frequent positive comments were associated with lower body dissatisfaction. However, both frequent negative and positive commentary were associated with higher drive for muscularity. Self-esteem was also associated with both body dissatisfaction and the drive for muscularity, but it did not moderate that influence of either positive or negative messages. Longitudinal research is now needed to determine the directionality of these relationships. Further research is required to establish the contexts in which positive and negative messages are associated with body dissatisfaction and the drive for muscularity.

Heavy tools manipulation by low powered direct-drive five-bar parallel robot

This paper presents a simple and available system for manipulation of heavy tools by low powered manipulator for industrial applications. In the heavy manufacturing industries, sometimes, heavy tools are employed for different types of work. But the application of robots with heavy tools is not possible due to the limited torque limits of actuators. Suspended tool systems (STS) have been proposed to manipulate heavy tools by low powered robot-arm for this purpose. A low powered five-bar direct-drive parallel manipulator is designed and constructed to manipulate heavy tools suspended from a spring balancer. The validity, usefulness, and effectiveness of the suspended tool system are shown by experimental results.

Kurdungurlu got to drive Toyota : differential colonizing process among the Warlpiri

This thesis is based on fieldwork I carried out between December 1987 and June 1989 while living with the residents of a small Warlpiri Outstation Community situated ca. 75 km north-west of Tennant Creek in the Northern Territory of Australia. Colonialism is a process whereby incommensurate gender regimes impact differently on women and men and this is reflected in the indigenous response which affects the socialization of Western things. The notion of the indigenous KIRDA-KURDUNGURLU reciprocity is shown to be consistent with a gender system and to articulate all exchange relations as pro-creative social relationships. This contrasts with the Western capitalist system of production and social reproduction of gendered individuals in that it does not ascribe gender to biological differences between women and men but is derived from a land based social division between Sister-Brother. Social relationships are put under great strain in an effort to socialize Western things for Warlpiri internal use, I argue that the colonization of Aboriginal societies is an ongoing process. Despite the historical shift from a physical all-male frontier to the present day cross-cultural negotiations between Aborigines and Non-Aborigines, men still privilege men. The negotiation process for ownership of a Community Toyota is the most recent phenomenon where this can be observed. Male privilege is established by linking control over the access to the Community Toyota with traditional rights to land. However, the Toyota as Western object has a Western gender identity as well. By pitting women against men it engages people in social conflict which is brought into existence through an organisation of Western concepts based on an alien gender regime. But Western things, especially the Community Toyota, resist socialization because the Warlpiri do not produce these things. Warlpiri people know this and, to satisfy their need for Western things, they engage them in a process of social differentiation. By this process they can be seen actively to maintain the Western system in an effort to maintain themselves as Warlpiri and to secure the production of Western things. This investigation of the cultural response to Western influences shows that indigenous gender relations are only maintained through a socially stressful process of socializing Western things.