29,502 research outputs found
Analyzing helicopter evasive maneuver effectiveness against rocket-propelled grenades
It has long been acknowledged that military helicopters are vulnerable to ground-launched threats, in particular, the RPG-7 rocket-propelled grenade. Current helicopter threat mitigation strategies rely on a combination of operational tactics and selectively placed armor plating, which can help to mitigate but not entirely remove the threat. However, in recent years, a number of active protection systems designed to protect land-based vehicles from rocket and missile fire have been developed. These systems all use a sensor suite to detect, track, and predict the threat trajectory, which is then employed in the computation of an intercept trajectory for a defensive kill mechanism. Although a complete active protection system in its current form is unsuitable for helicopters, in this paper, it is assumed that the active protection system’s track and threat trajectory prediction subsystem could be used offline as a tool to develop tactics and techniques to counter the threat from rocket-propelled grenade attacks. It is further proposed that such a maneuver can be found by solving a pursuit–evasion differential game. Because the first stage in solving this problem is developing the capability to evaluate the game, nonlinear dynamic and spatial models for a helicopter, RPG-7 round, and gunner, and evasion strategies were developed and integrated into a new simulation engine. Analysis of the results from representative vignettes demonstrates that the simulation yields the value of the engagement pursuit–evasion game. It is also shown that, in the majority of cases, survivability can be significantly improved by performing an appropriate evasive maneuver. Consequently, this simulation may be used as an important tool for both designing and evaluating evasive tactics and is the first step in designing a maneuver-based active protection system, leading to improved rotorcraft survivability
Design automation of microfluidic droplet sorting platforms
Both basic research and biological design require high throughput
screening to parse through the massive amounts of variants
generated in experiments. However, the cost and expertise
needed for use of such technology limit accessibility.
Simple and reproducible designs of a sorting platform
would reduce the barrier for implementation of affordable
bench-top screening platforms. Droplet microfluidics present
a promising approach for automating biology, reducing reaction
volumes to picoliter droplets and allowing for deterministic
manipulation of samples. Droplet microfluidics have
been used extensively for high throughput screening and
directed evolution, yet limitations in fabrication have
prevented the characterization needed for a design tool and
subsequent widespread adoption. Here, we present a finite
element analysis (FEA) model-based design framework for
dielectrophoretic droplet microfluidic sorters and its preliminary
experimental validation. This framework extends
previous work from our group creating microfluidic designs
tools, increasing their usability in the lab
Committed to Safety: Ten Case Studies on Reducing Harm to Patients
Presents case studies of healthcare organizations, clinical teams, and learning collaborations to illustrate successful innovations for improving patient safety nationwide. Includes actions taken, results achieved, lessons learned, and recommendations
Introduction
Crime-preventing neurointerventions (CPNs) are increasingly being used or advocated for crime prevention. There is increasing use of testosterone-lowering agents to prevent recidivism in sexual offenders, and strong political and scientific interest in developing pharmaceutical treatments for psychopathy and anti-social behaviour. Recent developments suggest that we may ultimately have at our disposal a range of drugs capable of suppressing violent aggression, and it is not difficult to imagine possible applications of such drugs in crime prevention. But should neurointerventions be used in crime prevention, and may the state ever permissibly impose CPNs as part of the criminal justice process? It is widely thought that preventing recidivism is one of the aims of criminal justice, yet existing means of pursuing this aim are often poorly effective, restrictive of basic freedoms, and harmful. Incarceration, for example, tends to be disruptive of personal relationships and careers, detrimental to physical and mental health, highly restrictive of freedom of movement and association, and rarely more than modestly effective at preventing recidivism. Neurointerventions hold the promise of preventing recidivism in ways that are more effective and more humane, but the use of CPNs in criminal justice raises several ethical concerns. CPNs could be highly intrusive and may threaten fundamental human values, such as bodily integrity and freedom of thought, and humanity has a track record of misguided, harmful, and unwarrantedly coercive use of neurotechnological ‘solutions’ to criminality. This collection brings together original contributions from emerging scholars and internationally renowned moral and political philosophers to address these issues
Resolution of Some Open Problems Concerning Multiple Zeta Evaluations of Arbitrary Depth
We prove some new evaluations for multiple polylogarithms of arbitrary depth.
The simplest of our results is a multiple zeta evaluation one order of
complexity beyond the well-known Broadhurst-Zagier formula. Other results we
provide settle three of the remaining outstanding conjectures of Borwein,
Bradley, and Broadhurst. A complete treatment of a certain arbitrary depth
class of periodic alternating unit Euler sums is also given.Comment: 21 pages, To appear in Compositio Mathematic
Communications for Next Generation single chip computers
It is the thesis of this report that much of what is presently thought to require specialized VLSI functions might instead be achieved by combinations of fast general purpose single chip computers with upgraded communication facilities. To this end, the characteristics of applications
of this nature are first surveyed briefly and some working principles established. In the light of these, three different chip philosophies are explored in some detail. This study shows that some upgrading of typical
single chip I/O will definitely be necessary, but that this upgrading does not have to be complex and that true multiprocessor-multibus operation could be achieved without excessive cost
Atmospheric Science and Remote Sensing Laboratory
During the contract year, scientific research on lightning and lightning hazards was carried out for the Atmospheric Electricity Group in the MSFC Remote Sensing Branch (ED43). These tasks included research on modeling the interaction of lightning optical pulses and cloud particles, estimating lightning hazard threats to the STS system, a small field project to determine the charge structure of winter and stratiform thunderstorms, and analysis of optical pulse data. These activities were performed in conjunction with the ED43 mission to develop a lightning mapper to be placed on one of the GOES-next operational satellites
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