Experiences applying Formal Approaches in the Development of Swarm-Based Space Exploration Systems

NASA is researching advanced technologies for future exploration missions using intelligent swarms of robotic vehicles. One of these missions is the Autonomous Nan0 Technology Swarm (ANTS) mission that will explore the asteroid belt using 1,000 cooperative autonomous spacecraft. The emergent properties of intelligent swarms make it a potentially powerful concept, but at the same time more difficult to design and ensure that the proper behaviors will emerge. NASA is investigating formal methods and techniques for verification of such missions. The advantage of using formal methods is the ability to mathematically verify the behavior of a swarm, emergent or otherwise. Using the ANTS mission as a case study, we have evaluated multiple formal methods to determine their effectiveness in modeling and ensuring desired swarm behavior. This paper discusses the results of this evaluation and proposes an integrated formal method for ensuring correct behavior of future NASA intelligent swarms

Challenges of Developing New Classes of NASA Self-Managing Mission

NASA is proposing increasingly complex missions that will require a high degree of autonomy and autonomicity. These missions pose hereto unforeseen problems and raise issues that have not been well-addressed by the community. Assuring success of such missions will require new software development techniques and tools. This paper discusses some of the challenges that NASA and the rest of the software development community are facing in developing these ever-increasingly complex systems. We give an overview of a proposed NASA mission as well as techniques and tools that are being developed to address autonomic management and the complexity issues inherent in these missions

Systems, methods and apparatus for generation and verification of policies in autonomic computing systems

Described herein is a method that produces fully (mathematically) tractable development of policies for autonomic systems from requirements through to code generation. This method is illustrated through an example showing how user formulated policies can be translated into a formal mode which can then be converted to code. The requirements-based programming method described provides faster, higher quality development and maintenance of autonomic systems based on user formulation of policies.Further, the systems, methods and apparatus described herein provide a way of analyzing policies for autonomic systems and facilities the generation of provably correct implementations automatically, which in turn provides reduced development time, reduced testing requirements, guarantees of correctness of the implementation with respect to the policies specified at the outset, and provides a higher degree of confidence that the policies are both complete and reasonable. The ability to specify the policy for the management of a system and then automatically generate an equivalent implementation greatly improves the quality of software, the survivability of future missions, in particular when the system will operate untended in very remote environments, and greatly reduces development lead times and costs

Aging and ultra-slow equilibration in concentrated colloidal hard spheres

We study the dynamic behaviour of concentrated colloidal hard spheres using Time Resolved Correlation, a light scattering technique that can detect the slow evolution of the dynamics in out-of-equilibrium systems. Surprisingly, equilibrium is reached a very long time after sample initialization, the non-stationary regime lasting up to three orders of magnitude more than the relaxation time of the system. Before reaching equilibrium, the system displays unusual aging behaviour. The intermediate scattering function decays faster than exponentially and its relaxation time evolves non-monotonically with sample age.Comment: Submitted to the proceedings of the 6th EPS Liquid Matter Conference, Utrecht 2-6 July 200

Autonomous and Autonomic Swarms

A watershed in systems engineering is represented by the advent of swarm-based systems that accomplish missions through cooperative action by a (large) group of autonomous individuals each having simple capabilities and no global knowledge of the group s objective. Such systems, with individuals capable of surviving in hostile environments, pose unprecedented challenges to system developers. Design and testing and verification at much higher levels will be required, together with the corresponding tools, to bring such systems to fruition. Concepts for possible future NASA space exploration missions include autonomous, autonomic swarms. Engineering swarm-based missions begins with understanding autonomy and autonomicity and how to design, test, and verify systems that have those properties and, simultaneously, the capability to accomplish prescribed mission goals. Formal methods-based technologies, both projected and in development, are described in terms of their potential utility to swarm-based system developers

Requirements of an Integrated Formal Method for Intelligent Swarms

NASA is investigating new paradigms for future space exploration, heavily focused on the (still) emerging technologies of autonomous and autonomic systems [47, 48, 49]. Missions that rely on multiple, smaller, collaborating spacecraft, analogous to swarms in nature, are being investigated to supplement and complement traditional missions that rely on one large spacecraft [16]. The small spacecraft in such missions would each be able to operate on their own to accomplish a part of a mission, but would need to interact and exchange information with the other spacecraft to successfully execute the mission

Quantum computation based on d-level cluster states

The concept of qudit (a d-level system) cluster state is proposed by generalizing the qubit cluster state (Phys. Rev. Lett. \textbf{86}, 910 (2001)) according to the finite dimensional representations of quantum plane algebra. We demonstrate their quantum correlations and prove a theorem which guarantees the availability of the qudit cluster states in quantum computation. We explicitly construct the network to show the universality of the one-way computer based on the defined qudit cluster states and single-qudit measurement. And the corresponding protocol of implementing one-way quantum computer can be suggested with the high dimensional "Ising" model which can be found in many magnetic systems.Comment: Revtex4, 15 pages, 3 eps figure

Treatment of acute diverticulitis laparoscopic lavage vs. resection (DILALA): study protocol for a randomised controlled trial

<p>Abstract</p> <p>Background</p> <p>Perforated diverticulitis is a condition associated with substantial morbidity. Recently published reports suggest that laparoscopic lavage has fewer complications and shorter hospital stay. So far no randomised study has published any results.</p> <p>Methods</p> <p>DILALA is a Scandinavian, randomised trial, comparing laparoscopic lavage (LL) to the traditional Hartmann's Procedure (HP). Primary endpoint is the number of re-operations within 12 months. Secondary endpoints consist of mortality, quality of life (QoL), re-admission, health economy assessment and permanent stoma. Patients are included when surgery is required. A laparoscopy is performed and if Hinchey grade III is diagnosed the patient is included and randomised 1:1, to either LL or HP. Patients undergoing LL receive > 3L of saline intraperitoneally, placement of pelvic drain and continued antibiotics. Follow-up is scheduled 6-12 weeks, 6 months and 12 months. A QoL-form is filled out on discharge, 6- and 12 months. Inclusion is set to 80 patients (40+40).</p> <p>Discussion</p> <p>HP is associated with a high rate of complication. Not only does the primary operation entail complications, but also subsequent surgery is associated with a high morbidity. Thus the combined risk of treatment for the patient is high. The aim of the DILALA trial is to evaluate if laparoscopic lavage is a safe, minimally invasive method for patients with perforated diverticulitis Hinchey grade III, resulting in fewer re-operations, decreased morbidity, mortality, costs and increased quality of life.</p> <p>Trial registration</p> <p>British registry (ISRCTN) for clinical trials <a href="http://www.controlled-trials.com/ISRCTN82208287">ISRCTN82208287</a><url>http://www.controlled-trials.com/ISRCTN82208287</url></p

The Sigma-trial protocol: a prospective double-blind multi-centre comparison of laparoscopic versus open elective sigmoid resection in patients with symptomatic diverticulitis

BACKGROUND: Diverticulosis is a common disease in the western society with an incidence of 33-66%. 10-25% of these patients will develop diverticulitis. In order to prevent a high-risk acute operation it is advised to perform elective sigmoid resection after two episodes of diverticulitis in the elderly patient or after one episode in the younger ( 50 years or in case of progressive abdominal complaints due to strictures caused by a previous episode of diverticulits. The diagnosis is confirmed by CT-scan, barium enema and/or coloscopy.It is required that the participating surgeons have performed at least 15 laparoscopic and open sigmoid resections. Open resection is performed by median laparotomy, laparoscopic resection is approached by 4 or 5 cannula. Sigmoid and colon which contain serosal changes or induration are removed and a tension free anastomosis is created. After completion of either surgical procedure an opaque dressing will be used, covering from 10 cm above the umbilicus to the pubic bone. Surgery details will be kept separate from the patient's notes.Primary endpoints are the postoperative morbidity and mortality. We divided morbidity in minor (e.g. wound infection), major (e.g. anastomotic leakage) and late (e.g. incisional hernias) complications, data will be collected during hospital stay and after six weeks and six months postoperative. Secondary endpoints are the operative and the postoperative recovery data. Operative data include duration of the operation, blood loss and conversion to laparotomy. Post operative recovery consists of return to normal diet, pain, analgesics, general health (SF-36 questionnaire) and duration of hospital stay. DISCUSSION: The Sigma-trial is a prospective, multi-center, double-blind, randomized study to define the role of laparoscopic sigmoid resection in patients with symptomatic diverticuliti