7,372 research outputs found
Evaluation of capacitors for space propulsion applications final progress report
Low inductance energy storage capacitors for space propulsion application
Thruster Allocation for Dynamical Positioning
Positioning a vessel at a fixed position in deep water is of great importance when working offshore. In recent years a Dynamical Positioning (DP) system was developed at Marin [2]. After the measurement of the current position and external forces (like waves, wind etc.), each thruster of the vessel is actively controlled to hold the desired location.
In this paper we focus on the allocation process to determine the settings for each thruster that results in the minimal total power and thus fuel consumption. The mathematical formulation of this situation leads to a nonlinear optimization problem with equality and inequality constraints, which can be solved by applying Lagrange multipliers.
We give three approaches: first of all, the full problem was solved using the MATLAB fmincon routine with the solution from the linearised problem as a starting point. This implementation, with robust handling of the situations where the thrusters are overloaded, lead to promising results: an average reduction in fuel consumption of approximately two percent. However, further analysis proved useful. A second approach changes the set of variables and so reduces the number of equations. The third and last approach solves the Lagrange equations with an iterative method on the linearized Lagrange problem
The Physiology of Social-Emotional Learning: Integrating Biomarkers of Self-Regulation into the Assessment and Implementation of Programs
In the last two decades, formalized social-emotional learning (SEL) programs in schools have proliferated in response to a staggering increase in mental, social, and emotional challenges for youth. SEL programs differ in their theoretical foundations, though there are commonalities among them. Self-regulation (SR) surfaces as an important pillar. Researchers have relied mostly on self-reporting and teacher questionnaires to measure the effectiveness of these programs to improve SR and other aspects of youth well-being, without explicitly considering the physiological effects of these interventions on the biomarkers of youth. By addressing this gap, program researchers, developers, and educators can reach their stated objectives more effectively, thereby better nurturing SR and other social-emotional competencies. This paper explores a new model and rationale for incorporating physiological metrics (biomarkers), such as vagal tone (VT), into current SEL program impact-assessments and recommends incorporating mind-body practices such as exercise, breathing, mindfulness, and yoga into SEL interventions. This model hypothesizes that the integration of physiological measures and the practices that affect these markers will lead to an increase in SR via a bidirectionally-causative upward spiral. Recommendations for school-based interventions to affect VT are discussed, along with considerations for implementation
Growth of aerobic and anaerobic bacteria in agar subjected to freezing and diurnal freezing and thawing
Aerobic and anaerobic bacteria growth in agar after freezing and diurnal freezing and thawin
Sampling and handling of desert soils
Sampling and handling of desert soils - area site, transportation, processing, and storag
Hysteresis phenomenon in deterministic traffic flows
We study phase transitions of a system of particles on the one-dimensional
integer lattice moving with constant acceleration, with a collision law
respecting slower particles. This simple deterministic ``particle-hopping''
traffic flow model being a straightforward generalization to the well known
Nagel-Schreckenberg model covers also a more recent slow-to-start model as a
special case. The model has two distinct ergodic (unmixed) phases with two
critical values. When traffic density is below the lowest critical value, the
steady state of the model corresponds to the ``free-flowing'' (or ``gaseous'')
phase. When the density exceeds the second critical value the model produces
large, persistent, well-defined traffic jams, which correspond to the
``jammed'' (or ``liquid'') phase. Between the two critical values each of these
phases may take place, which can be interpreted as an ``overcooled gas'' phase
when a small perturbation can change drastically gas into liquid. Mathematical
analysis is accomplished in part by the exact derivation of the life-time of
individual traffic jams for a given configuration of particles.Comment: 22 pages, 6 figures, corrected and improved version, to appear in the
Journal of Statistical Physic
Atrial high-rate episodes: prevalence, stroke risk, implications for management, and clinical gaps in evidence
Self-terminating atrial arrhythmias are commonly detected on continuous rhythm monitoring, e.g. by pacemakers or defibrillators. It is unclear whether the presence of these arrhythmias has therapeutic consequences. We sought to summarize evidence on the prevalence of atrial high-rate episodes (AHREs) and their impact on risk of stroke. We performed a comprehensive, tabulated review of published literature on the prevalence of AHRE. In patients with AHRE, but without atrial fibrillation (AF), we reviewed the stroke risk and the potential risk/benefit of oral anticoagulation. Atrial high-rate episodes are found in 10-30% of AF-free patients. Presence of AHRE slightly increases stroke risk (0.8% to 1%/year) compared with patients without AHRE. Atrial high-rate episode of longer duration (e.g. those >24 h) could be associated with a higher stroke risk. Oral anticoagulation has the potential to reduce stroke risk in patients with AHRE but is associated with a rate of major bleeding of 2%/year. Oral anticoagulation is not effective in patients with heart failure or survivors of a stroke without AF. It remains unclear whether anticoagulation is effective and safe in patients with AHRE. Atrial high-rate episodes are common and confer a slight increase in stroke risk. There is true equipoise on the best way to reduce stroke risk in patients with AHRE. Two ongoing trials (NOAH-AFNET 6 and ARTESiA) will provide much-needed information on the effectiveness and safety of oral anticoagulation using non-vitamin K antagonist oral anticoagulants in patients with AHRE.info:eu-repo/semantics/publishedVersio
Electrodeposition in capillaries: bottom-up micro- and nanopatterning of functional materials on conductive substrates
A cost-effective and versatile methodology for bottom-up patterned growth of inorganic and metallic materials on the micro- and nanoscale is presented. Pulsed electrodeposition was employed to deposit arbitrary patterns of Ni, ZnO, and FeO(OH) of high quality, with lateral feature sizes down to 200–290 nm. The pattern was defined by an oxygen plasma-treated patterned PDMS mold in conformal contact with a conducting substrate and immersed in an electrolyte solution, so that the solid phases were deposited from the solution in the channels of the patterned mold. It is important that the distance between the entrance of the channels, and the location where deposition is needed, is kept limited. The as-formed patterns were characterized by high resolution scanning electron microscope, energy-dispersive X-ray analysis, atomic force microscopy, and X-ray diffraction
Penetration of Anionic Surfactants into Skin II. Study of Mechanisms Which Impede the Penetration of Synthetic Anionic Surfactants into Skin11From the Research Laboratories of the Department of Dermatology of the Harvard Medical School at the Massachusetts General Hospital, Boston 14, Massachusetts.This investigation was supported by grants from the U. S. Army Chemical Corps (Contract DA 18-108-405-CML-672) and from the Division of Medical Sciences of the Department of Health, Education and Welfare, U. S. Public Health Service, National Institutes of Health (Grant RG-4760).We wish to thank Colgate-Palmolive Co., Lever Brothers Co., The Procter and Gamble Co., Monsanto Chemical Co., and California Research Corporation for the various surfactants used in this investigation. Mr. Roy W. Peet, Manager of the Association of American Soap and Glycerine Producers, Inc., helped us make contact with the surfactant manufacturers.
An Isolated Human Skeleton from Southern Ohio
Author Institution: Department of Anthropology, Cleveland State UniversityDuring the recent construction of the Ross County Regional Water System in Southern Ohio, the skeletal remains of a prehistoric American Indian were recovered. The isolated burial remains represent the skeleton of a male, between 40 and 45 years of age. The discovery circumstances prevent accurate determination of the date of deposition. An extensive examination of the skeletal remains suggests the occurrence of several pathological lesions among which are: a healed fracture of the left clavicle, osteoarthritis of the joint surfaces of the long bones and vertebrae, periostitis of the lower limbs, cribra orbitalia, and an advanced case of Leggs-Calve-Perthes Disease
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