A microprogrammed operating system kernel

The subject of the thesis is the design and implementation of an operating system kernel for the Cambridge Capability Computer (CAP). The kernel of an operating syst em is its most primitive level of facilities and forms the foundation stone a round which t he rest of the system is structured. The particular emphasis of the CAP kernel is concerned with protection - the control of access to information. The kernel uses the notion of capabilities to provide a flexible and controlled mechanism for the sharing of information within a computer system. The protection mechanisms include provision for the efficient control of access to memory as well as facilities for handling abstract resources like files and virtual peripherals. The kernel allows the introduction of new types of resources in addition to the basic set of hardware resourcee to permit user extension of the system. Attention is given to the problem of recall of privilege or revocation in capability systems and the kernel includes operations for both permanent and temporary revocation of particular access rights to information in a selective manner. In the past many of these functions have only been found in kernels implemented in user-level software which arc frequently cumbersome and inefficient. An examination is made of why this should be and·how efficiency and simplicity can be gained by a microprogrammed implementation. The thesis draws on the experience of a number of soft.ware kernels to discover the various design decisions that have to be made and the techniques that may be used to implement a successful kernel. The feasibility of the design arrived at by considering these issues is demonstratec1 by describinq its implementation on the Cambridge Capability Computer in terms of the primitives provided and the internal organisation of the proposed kernel. In an evaluation, the kernel is examined in the light of the analysis of other kernels to point out its strength s and weaknesses and to gain insights into the utility of the deign as a practical operating system kernel.Digitisation of this thesis was sponsored by Arcadia Fund, a charitable fund of Lisbet Rausing and Peter Baldwin

What is the Impact of Software Patent Shifts?: Evidence from Lotus v. Borland

Economists have debated the extent to which strengthening patent protection spurs or detracts from technological innovation. In this paper, we examine the reduction of software copyright protection in the Lotus v. Borland decision. If patent and copyright protections are substitutes, then weakening of one form of protection should be associated with an increasing reliance on the other. We find that the firms affected by the diminution of copyright protection disproportionately accelerated their patenting in subsequent years. But little evidence can be found for harmful effects: in fact, the increased reliance on patents is correlated with some positive outcomes for firms.

Child L2 development: a longitudinal case study on voice onset times in word-initial stops

This paper reports the results of a longitudinal case study examining the acquisition of the English voice system by a three-year-old native speaker of Dutch. The Study aims to examine whether the child develops two different phonetic systems or uses just one system for both languages, and compares the early L2 acquisition process with L1, simultaneous bilingual and late L2 acquisition. The results reveal that the child successfully acquires the English contrast between short-lag and long-lag stops, but gradually changes the Dutch system, which contrasts prevoiced with short-lag stops, into the direction of the English system

A Study of IEEE 802.15.4 Security Framework for Wireless Body Area Network

A Wireless Body Area Network (WBAN) is a collection of low-power and lightweight wireless sensor nodes that are used to monitor the human body functions and the surrounding environment. It supports a number of innovative and interesting applications, including ubiquitous healthcare and Consumer Electronics (CE) applications. Since WBAN nodes are used to collect sensitive (life-critical) information and may operate in hostile environments, they require strict security mechanisms to prevent malicious interaction with the system. In this paper, we first highlight major security requirements and Denial of Service (DoS) attacks in WBAN at Physical, Medium Access Control (MAC), Network, and Transport layers. Then we discuss the IEEE 802.15.4 security framework and identify the security vulnerabilities and major attacks in the context of WBAN. Different types of attacks on the Contention Access Period (CAP) and Contention Free Period (CFP) parts of the superframe are analyzed and discussed. It is observed that a smart attacker can successfully corrupt an increasing number of GTS slots in the CFP period and can considerably affect the Quality of Service (QoS) in WBAN (since most of the data is carried in CFP period). As we increase the number of smart attackers the corrupted GTS slots are eventually increased, which prevents the legitimate nodes to utilize the bandwidth efficiently. This means that the direct adaptation of IEEE 802.15.4 security framework for WBAN is not totally secure for certain WBAN applications. New solutions are required to integrate high level security in WBAN.Comment: 14 pages, 7 figures, 2 table

A summary of AFCRL passive-sphere development efforts and experience

Falling spheres for meteorological rocket soundin

A framework for realistic 3D tele-immersion

Meeting, socializing and conversing online with a group of people using teleconferencing systems is still quite differ- ent from the experience of meeting face to face. We are abruptly aware that we are online and that the people we are engaging with are not in close proximity. Analogous to how talking on the telephone does not replicate the experi- ence of talking in person. Several causes for these differences have been identified and we propose inspiring and innova- tive solutions to these hurdles in attempt to provide a more realistic, believable and engaging online conversational expe- rience. We present the distributed and scalable framework REVERIE that provides a balanced mix of these solutions. Applications build on top of the REVERIE framework will be able to provide interactive, immersive, photo-realistic ex- periences to a multitude of users that for them will feel much more similar to having face to face meetings than the expe- rience offered by conventional teleconferencing systems

SEMA4A: An ontology for emergency notification systems accessibility

This is the post-print version of the final paper published in Expert Systems with Applications. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2009 Elsevier B.V.Providing alert communication in emergency situations is vital to reduce the number of victims. Reaching this goal is challenging due to users’ diversity: people with disabilities, elderly and children, and other vulnerable groups. Notifications are critical when an emergency scenario is going to happen (e.g. a typhoon approaching) so the ability to transmit notifications to different kind of users is a crucial feature for such systems. In this work an ontology was developed by investigating different sources: accessibility guidelines, emergency response systems, communication devices and technologies, taking into account the different abilities of people to react to different alarms (e.g. mobile phone vibration as an alarm for deafblind people). We think that the proposed ontology addresses the information needs for sharing and integrating emergency notification messages over distinct emergency response information systems providing accessibility under different conditions and for different kind of users.Ministerio de Educación y Cienci